Unit 1 & 2 Biology Exam

*Recall chemical equations for photosynthesis and respiration, and explain the energy changes associated with each [chapter 4]

photosynthesis: carbon dioxide + water (sunlight) --> glucose + oxygen 6CO2 + 6H2O --> C6H12O6 + 6O2 respiration: glucose + oxygen --> carbon dioxide + water + energy C6H12O6 + 6O2 --> 6CO2 + 6H2O + ATP

describe how receptor binding activates a signal transduction mechanism and alters cellular activity (results in an increase or decrease in normal processes) [chapter 9]

signal transduction: a set of chemical reactions in a cell that occurs when a molecule, such as a hormone, attaches to a receptor on the cell membrane - Hormones act on specific target cell/organ - target cells contain receptors on the cell surface to receive the hormone (shape of hormone fits the specific receptor) When a hormone arrives at the target cell there are three stages of signal transduction that occur: 1. reception - hormone arrives at target cell and binds to receptors 2. transduction - binding activates the receptor and changes its shape to trigger a series of biochemical processes inside the cell to stimulate a specific response 3. response - the response can be: activating enzymes, removing molecules from the cell (exocytosis), switching genes on or off and opening protein channels to allow substances in or out

recognise how a cell's sensitivity to a specific hormone is directly related to the number of receptors it displays for that hormone (including upregulation and downregulation) [chapter 9]

- target cells contain receptors on cell surface receive specific hormones (hormones are only active in cells where the shape of hormone and receptor fit like a lock and key) An increase in receptors = upregulation - if the cell receives a weak signal, more receptors can be produced to increase the cell's sensitivity to the message A decrease = downregulation - membrane receptors can be removed to reduce the cell's sensitivity to a message

describe the inflammatory response (prostaglandins, vasodilation, phagocytes) and the role of the complement system [chapter 11]

- the inflammatory response assists the second line of defence INFLAMMATORY RESPONSE 1. The first line of defence is breached when tissue damage occurs 2. Pathogens enter the wound and release cytokines (chemical (alarm) that tells the body there is trouble) that initiates the inflammatory response 3. Mast cells release a chemical called histamine, which causes local vasodilation and increased capillary permeability (causing the areas to become heated and reddened) 4. Platelets move out of the capillary to seal the wounded area 5. Pathogens are attacked by phagocytes (eat antigens), one type of phagocyte is a neutrophil. Neutrophils are small enough to squeeze through the walls of a capillary to reach the site of infection. They then engulf and destroy any pathogens they enter. 6. Another type of phagocyte is the larger, less abundant macrophage, which consumes and destroys any pathogens they encounter and rid the body of worn-out cells and debris. Some macrophages are stationed in the tissues of the body and await pathogens, while others move through tissues and seek out pathogens. 7. Eosinophils discharge destructive enzymes to destroy pathogens too big for phagocytes (eg. parasitic worms) 8. When a serious infection occurs, the immune system responds in two ways. It produces more white blood cells and phagocytes release chemicals such as histamine that increase body temperature (fever) which offers powerful protection against the spread of pathogens by stopping or slowing the growth of some microbes. COMPLEMENT SYSTEM - distinguishing between self and non-self, not attack (helps inflammation) complement system: a system of proteins which, when activated by the presence of an antigen, produce chemicals that bring about inactivation of foreign matter - self: MHC proteins (stamp) are on all self cells which tell the immune system not to attack its own cells (occur within the body eg. allergens) - non-self: pathogens have their own set of proteins displayed on the surface of their cells (antigens that originate outside the organism eg. bacteria and viruses) - any non-self-marker is known as an antigen to the host organism, and it will initiate the immune response - antigens are proteins foreign to the host announces the pathogen as foreign (they induce an immune response) - it is necessary for the body to recognise its own cell's antigens so that it doesn't attack, and to identify unknown (foreign) antigens so that an immune response can destroy the pathogens - about 20 complement proteins present in the bloodstream - usually inactive until required - work in two ways: 1. opsonisation (snitching on pathogens) 2. membrane attack complex (stabbing the pathogen) 1. opsonisation: - proteins "tag" pathogen by covering the surface - when phagocytes recognise antigens, complement proteins help attach pathogen to phagocytes 2. membrane attack complex: - the protein attaches to the pathogen and makes a hole in the pathogen membrane - fluid rushes in and makes the pathogen undergo lysis (breaking the cell) where the pathogen is destroyed

recognise that sensory receptors (chemo, thermos, mechano, photo, noci) detect stimuli and can be classified by the type of stimulus [chapter 9]

- they body knows that there is a change in the internal or external environment using specific sensory receptors for certain stimuli chemoreceptors: external: - concerned with taste and smell (tongue and nose) in tastebuds, taste receptor cells detect a change in chemical substance internal: - monitor blood chemistry (detect changes in levels) - oxygen and carbon dioxide as well as pH thermoreceptors: - detect temperature changes either internally (hypothalamus) in the blood or externally (skin) due to environment mechanoreceptors: - touch, pressure, stretching, movement, itching and vibration - found in skin/epidermis photoreceptors: - detect light, colour and images (eyes) - rods and cones nociceptors: - pain receptors (free nerve endings detect pain in the skin, muscles, joints, gut etc.)

explain the process of the passage of a nerve impulse in terms of transmission of an action potential (conduction within neuron) and synaptic transmission (communication between neurons) [chapter 9]

- neurons carry impulses from receptors (sensory neurons) to regulators (CNS - brain and spinal cord) and then to effectors (motor neurons - muscles/glands) transmission of an impulse: - neurons are stimulated by electrical signals received by dendrites - the soma receives the action potential and the signal passes along the axon as it jumps between the nodes of Ranvier to speed up the transmission to the terminal buttons - once the message has arrived at the terminal buttons, it is passed through the diffusion of neurotransmitters through the synapse to the next neuron synaptic transmission: - the synapse is the connection between two neurons from the axon terminal to dendrites - the synaptic knob contains vesicles with neurotransmitters when the electrical impulse arrives - they diffuse from the presynaptic neurons across the synaptic cleft and combine with receptors (dendrites) on the postsynaptic neuron to continue the process of transferring the impulse

Recognise simple nutrients in the form of monosaccharides, disaccharides, polysaccharides, amino acids, fatty acids, glycerol, nucleic acids, ions and water [chapter 2]

- Carbohydrates: Organic Cellular respiration = ATP Monosaccharides+Disaccharides + Polysaccharides are monomers Monosaccharides: Carbohydrate, a single sugar molecule Disaccharides: Carbohydrate, two sugar molecules linked Polysaccharide: Carbohydrate, many sugar molecules linked - Lipids (fats): Organic Fatty acids + Glycerol are monomers Metabolic processes = ATP + other processes in body Two sub-categories (saturated and unsaturated) Fatty acids: component of lipids. Formed between a carboxyl group and a chain of hydrocarbons Glycerol: a structural component of lipids - Proteins: Organic Are made of 20 different amino acids (monomers) Some are made in the body others come from diet Metabolic processes = enzymes + hormones, building blocks of bones, muscles, cartilage, skin and bone Amino acids: building blocks of protein, join together to form chains (enzymes and hormones are proteins) - Nucleic acids: Overall name for DNA and RNA Information carrying molecules composed of nucleotides (monomer) make up the genetic material in living things. Two types: DNA and RNA. consist of a phosphate, nitrogen base and sugar - Vitamins: Organic Essential nutrients needed in small amounts Can't be synthesized by humans 13 recognised vitamins - Ions (minerals): Inorganic charged atom or molecule Usually exist as ions in solutions - Water: Inorganic Regulates temperature and maintains other bodily functions - Matter: CO2 and O2 Inorganic Needed to create energy through cellular respiration or photosynthesis (Calvin cycle)

identify from given data and describe the following modes of disease transmission: direct contact, contact with body fluids, contaminated food, water and disease-specific vectors [chapter 11]

- modes of disease transmission are how diseases spread (there is no single model to describe the transmission of pathogens from one individual to another): 1. Direct/indirect contact Direct: - pathogen transmitted by physical contact between two individuals through actions eg. touching Indirect: - when objects become contaminated with a pathogen, new host touches the object becomes infected 2. Contact with bodily fluids - when an individual coughs/sneezes, small droplets of mucus may contain pathogens ejected (eg. breastmilk, kissing/sexual intercourse - saliva/semen, blood (sharing needles) - AIDS/HIV 3. Contaminated food/water - food poisoning (salmonella) - cholera causes diarrhoea 4. Disease-specific vector - any agent that carries and transmits an infectious pathogen into another living organism vector: an organism that does not cause disease itself but spreads infection by transferring pathogens from one host to another eg. flies, mosquito, ticks - malaria

Understand that eukaryotic cells have specialised organelles to facilitate biochemical processes [chapter 3]

- nucleus (control centre of the eukaryotic cell for the reactions) - photosynthesis (chloroplasts) - cellular respiration (mitochondria) - synthesis of complex molecules including proteins (rough endoplasmic reticulum), carbohydrates, lipids and steroids (smooth endoplasmic reticulum), pigments, tannins and polyphenols (plastids) - the removal of cellular products and wastes (lysosomes)

recall examples of physical defence strategies and chemical defence strategies of plants in response to the presence of pathogens [chapter 11]

- The main plant pathogens are viroids, viruses, bacteria, fungi, protozoa, ectoparasites - Although lacking an adaptive immune system, plants exhibit a large array of innate mechanisms to inhibit entry, detect invading organisms and stop them before they are able to cause extensive damage - Passive/innate defence mechanisms (physical and chemical): physical defence strategies: - barriers (impenetrable barriers, such as bark, waxy cuticles and cell walls, which are resistant to many pathogens) - thorns (modified branches), spines (modified leaves) or prickles (outgrowths of the epidermis) to protect against grazing animals - leaf structures (plants are subject to attack by herbivores, many have leaf hairs (often containing chemicals) to defend them against insect pests) - thick waxy cuticle on their leaves, prevents the formation of a moisture film on the leaf surface as dry surfaces inhibit infection by bacteria and fungi - stomata are natural openings in the plant for both pathogens and their vectors and stomatal size relative to the size of the pathogen may be important chemical defence strategies: - optimal pH range for the soil in which it grows, and this acidity or alkalinity can exclude some pathogens - plant defensins (plant defensin is a protein produced by a plant to inhibit development of fungi, bacteria and viruses) - production of toxins (phytoanticipin is a chemical produced by plants to inhibit fungal spore germination)

explain how the structure and function of capillaries facilitates the exchange of materials (water, oxygen, carbon dioxide, ions and nutrients) between the internal environment and cells [chapter 6]

- oxygenated blood travels to body cells - arteries divide into capillaries to ensure all cells receive oxygen - oxygen and nutrients diffuse into interstitial fluid then into cells - proteins and cells too big for the capillary wall - water is forced into the interstitial fluid (osmosis - low to high solute concentration) as pressure increases - water is re-absorbed into the blood due to low pressure in the venule - excess water absorbed by the lymph system - CO2 diffuses out of the cell into fluid then into the blood - cellular waste is absorbed by the blood

*Describe the differences between types of organic molecules, what roles they have in cells, and why they fit these roles well [chapter 2]

- a complex carbon compound formed by living things; usually a macromolecule The main organic compounds in living things are: - carbohydrates: hydrated carbons, its monomer is called a monosaccharides eg. glucose (important energy sources) and can be stored as polysaccharides eg. starch in plants - proteins they help in metabolism by providing structural support and by acting as enzymes, carriers, or hormones. The building blocks of proteins (monomers) are amino acids - lipids are fats, oils and waxes which play an important role in the control of water balance in the organism, an important component of the membranes surrounding cells - nucleic acids macromolecules that make up the genetic material of all living organisms. two principal types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) - vitamins. organic chemicals, most of which animals cannot make for themselves but must obtain from their diets and are essential, in small amounts, for normal cell reactions

explain the role stem cells play in the development of a multicellular organism, and in growth and tissue repair [chapter 5]

- adult stem cells - stem cells found in the body after birth are responsible for repair and maintenance of the adult body - they are signalled by other molecules to move across the membrane or genes in the cells are switched on or off (cells divide by mitosis for growth and repair) - the three germ layers of the stem cells are the origin for different tissue development in an animal (ectoderm - skin, nervous system; mesoderm - skeleton, muscles, kidneys; endoderm - digestive, respiratory and urinary system) - in plants, meristem cells can divide into daughter cells that specialise

describe the role of digestive enzymes (amylase, protease, lipase) in chemical digestion [chapter 7]

- although food is digested physically by the mouth and stomach, it needs further chemical digestion Digestion - breaking down food into nutrients which the body uses for growth, energy and repair mouth: ph is neutral (7) - salivary glands secrete saliva containing amylase enzyme (breaks down starch to maltose and glucose) stomach: ph is acidic (2) - glands in the stomach secrete gastro juice (pepsin enzyme) to break down proteins into amino acids small intestine: ph is neutral/alkaline (8) - pancreas secretes lipase enzyme to further emulsify fats/lipids to triglycerides and glycerol

interpret long-term immune response data [chapter 11]

- be able to interpret data (independant on x-axis, dependant on y-axis)

*explain the exchange of materials between cells and blood at capillary beds [chapter 6]

- blood is carried through the body through blood vessels - the heart is the organ that pumps blood - capillaries are small blood vessels that have a wall which is one endothelial thick Oxygen, carbon dioxide, nutrients, and wastes are exchanged from cells to the blood and from the blood to cells through the thin walls of the capillaries

recognise the difference between plants and animals immune responses [chapter 11]

- both plants and animals have innate immune responses (general/non-specific) - vertebrates also have adaptive (specific) immune responses, plants don't

*investigate the effect of an antimicrobial on the growth of a microbiological organism (via the measurement of zones of inhibition) — laboratory or virtual [chapter 11]

- different types of antibiotics or disinfectants are placed on an inoculated agar plate - if the bacteria are susceptible to the chemical, then a zone of inhibition of bacterial growth is seen as a clear area around the disk. - the size of this zone is an indication of the effectiveness of the chemical being tested - if there is no cleared area around the disk, it is an indication that the bacterium is resistant to that chemical

use data presented as diagrams, schematics and tables to predict the direction in which materials will be exchanged between: a) alveoli and capillaries, and b) capillaries and muscle tissue [chapter 6]

- gases diffuse from high to low concentration of solutes - water diffuses by osmosis from low to high solute, high to low pressure across a membrane - oxygen diffuses into the blood via the alveoli and carbon dioxide diffuses out - active transport is when particles move against a concentration gradient using energy as molecules are too big

*refer to lungs, small intestine, and kidneys to describe the characteristics of an exchange surface [chapter 7]

- large surface area for maximum gas absorption - moist surface to dissolve ions - one or two cells thick (thin membrane) for easy gas exchange/transfer - surrounded by many capillaries for maximum gas exposure and extensive blood flow

Recognise the requirements of all cells for survival [chapter 2]

- matter - Gases (carbon dioxide and oxygen) - Ions and water - Organic compounds in the form of carbohydrates (monosaccharides, disaccharides, polysaccharides) - Protein (amino acids) - Lipids (fatty acids and glycerol) - Nucleic acids (DNA) - Energy sources (energy released from a chemical reaction and light energy from the sun)

explain how water and dissolved minerals move through xylem via the roles of root pressure, transpiration stream and cohesion of water molecules [chapter 8]

- water moves upward through the xylem from the roots to leaves for evaporation due to to the cohesive and adhesive properties of water - most of the water absorbed from the soil is lost by evaporation from leaves and stem (stomata), called transpiration - the flow of water through the plant is called transpiration stream (gradient in solute concentration that increases from roots to air - driving force that allows water to move passively via osmosis up the plant - helps the plant take up minerals) The transpirational stream is achieved by: - osmosis along a diffusion gradient between the leaves and the roots and soil - root pressure, causing water to move up the stem a limited distance until counteracted by the force of gravity - adhesion of water molecules to the walls of the xylem elements and the spongy mesophyll cells - cohesion between the water molecules, forming thin water columns in the xylem transpiration, causing a water loss from the stomata of the leaves. Root pressure: - the pressure exerted on water in the roots of plants due to the continued uptake of water from the soil by osmosis; it forces water a certain way up the stem of the plant until counteracted by the force of gravity Transpiration stream: - Water (containing dissolved mineral ions) enters through the root hairs of land plants. The water movement is in one direction only, from roots to leaves, and is referred to as the transpiration stream. The cohesion of water: - Cohesive properties of water - cling together - Adhesive properties - adhere to walls of the xylem This upward pull of cohesion creates constant tension which helps water uptake and movement up the plant

interpret feedback control diagrams for either nervous or hormonal systems [chapter 9]

1. stimulus change in the environment of an organism that brings about a response 2. receptors sense organ - a cell or group of cells that receive stimuli 3. control centre/coordinating system/regulator a substance or process that regulates or controls another 4. appropriate effector an organ or cell by which an animal acts, e.g. muscles, glands 5. response the reaction of an organism to a particular stimulus Feedback: - modification or control of a process or system by its results or effects, e.g. in a biochemical pathway or behavioural response positive feedback: - a physiological control mechanism in which a change in some variable triggers mechanisms that amplify the change - occurs to increase a change or output - the result of a reaction is amplified to make it occur more quickly eg. childbirth negative feedback: - a change which reverses a particular trend - occurs to reduce change or output - the result of a reaction is to reduce/bring the system back to normal eg. shivering

analyse these factors to predict potential outbreaks [chapter 12]

All epidemiological studies include: - persistence of pathogens within the host - transmission mechanism - how common the disease is (the number of people affected) - how many people in the population died as a result of the disease - the proportion of the population that is immune or has been immunised - mobility of individuals in the affected population e.g. age, gender, race, diet, geographic location, lifestyle, and family history of the disease - how they can increase/decrease potential outbreaks (epidemic, pandemic)

identify cells that transport nerve impulses from sensory receptors to neurons to effectors [chapter 9]

A typical nerve cell, or neuron, consists of a cell body (soma) which contains the nucleus and from which extend fibres (dendrites or axons). Information is carried from cell to cell by electrical impulses (called action potentials) that are generated by changes in ions across the neuron membrane. - Neuron - one cell that transmits information through a chemical/electrical impulse. - hormones are slow and long-lasting - the nervous system is a short and fast response CNS (brain and spinal cord) PNS (somatic - voluntary/receptors, muscles and autonomic - involuntary/heart rate, breathing) - In the PNS (sympathetic - increases energy, parasympathetic - conserves energy)

identify the characteristics of absorptive surfaces within the digestive system and relate to the structure and function of the villi [chapter 7]

Absorption of nutrients involves osmosis, diffusion and active transport. Villi in the small intestine in the digestive system: Functions/characteristics: - slows down the movement of food - increases the surface area for absorption - they sway to mix the content villi - a finger-like projection of the lining of the small intestine; increases the surface area available for absorption - the epithelial layer of villi has extensions called microvilli to increase the surface are - each villus has a network of capillaries and lacteal tubes to transport nutrients away (carbohydrates/glucose, proteins/amino acids, fats/lipids) microvilli - a projection from the surface of cells; forms a brush border that increases the surface area of the cell membrane

Identify the differences between aerobic and anaerobic respiration [chapter 4]

Aerobic Respiration: Is the complete conversion of glucose to carbon dioxide and water in the mitochondria of cells with oxygen present, resulting in a large release of energy (net gain of 36 ATP) Anaerobic respiration: Is cellular respiration in the absence of oxygen, resulting in a net gain of 2 ATP and lactic acid (in animals), or ethyl alcohol and carbon dioxide (in plants and fungi)

identify the interrelated factors affecting immunity [chapter 12]

All epidemiological studies include: - persistence of pathogens within the host - transmission mechanism - how common the disease is (the number of people affected) - how many people in the population died as a result of the disease - the proportion of the population that is immune or has been immunised - mobility of individuals in the affected population e.g. age, gender, race, diet, geographic location, lifestyle, and family history of the disease

Explain, using an example, how the arrangement of internal membranes can control biological processes [chapter 3]

Biochemical processes in the cell are controlled by the nature and arrangement of internal membranes. For example: - chloroplasts: chloroplasts are large, consisting of a fluid matrix or stroma and stacks of flattened membranous discs called grana (singular stack = granum). Each disc is termed a thylakoid. They contain chlorophyll and function in photosynthesis. - mitochondria: folding of membranes in mitochondria increases the surface area for enzyme-controlled reactions

Recognise that prokaryotic and eukaryotic cells have many features in common, which is a reflection of their common evolutionary past [chapter 3]

Both prokaryotic and eukaryotic cells have structures in common such as both containing a cell (plasma) membrane, cytoplasm, ribosomes and DNA. One view of the evolution of the eukaryotic cell is the endosymbiotic hypothesis. According to this hypothesis, there was such a strong symbiotic relationship between a small group of prokaryotic cells that they became permanently integrated, with smaller cells living inside a larger cell. These smaller cells became the organelles of the eukaryotic cell.

Recognise that biochemical processes are controlled and regulated by a series of specific enzymes [chapter 2]

Cells cannot tolerate too much heat since many biological compounds decompose at high temperatures. Therefore, the biological catalysts found in living systems that control and regulate biochemical processes are called enzymes. enzymes - globular proteins that lower the activation energy needed for a chemical reaction to take place, speeding up the rate of the reaction without altering the temperature at which it occurs eg. lipase, transferase, catecholase (specific) - they lower activation energy and speed up the rate of reaction by changing the shape of a substrate (pressure) to make bonds break more easily - don't alter products, aren't used up

recall that effectors are either muscles or glands [chapter 9]

Effectors are parts of the body - such as muscles and glands - that produce a response to a detected stimulus. For example, a muscle contracting to move an arm or a gland releasing a hormone into the blood. Effectors can be either muscles (which contract in response to neural stimuli) or glands (which produce secretions from hormonal stimuli).

recognise that the transmission of the disease is facilitated by the regional and global movement of organisms [chapter 12]

Epidemiology is the scientific study of factors determining and influencing the frequency and distribution of disease, injury and other health-related events in a defined human population. Its purpose is to establish programs to prevent and control their development and spread. It can be used to evaluate health services and preventative programs or to identify individuals who are at high risk of contracting a disease.

explain why changes in metabolic activity alter the optimum conditions for the catalytic activity of enzymes (with reference to tolerance limits) [chapter 9]

For an organism to survive and function in a particular habitat, it must be within its tolerance for all environmental factors (the upper and lower limits to the range of particular environmental factors e.g. light, temperature, availability of water within which an organism can survive). Enzyme activity can be affected by a variety of factors, such as temperature, pH, and concentration. - Extremely high temperatures can cause an enzyme to lose its shape (denature) and stop working - pH: Each enzyme has an optimum pH range. Changing the pH outside of this range will slow enzyme activity. - optimal enzyme action shows the significance of homeostasis, as specific metabolic processes occur due to appropriate pH levels and temperature. - optimal level: state of something that is the most appropriate for an outcome to occur - tolerance limit: the upper/lower limit to the range of a particular environmental or physiological factor for an organism to survive

recall that what the process of homeostasis involves [chapter 9]

Homeostatic mechanisms operate via a feedback loop that may involve either the nervous or endocrine systems (or both): - When specialised receptors detect an internal change to conditions, a response is generated to correct the change - Most homeostatic responses involve an effect that is antagonistic to the detected stimulus (negative feedback) - When levels return to equilibrium, the effector ceases to generate a response and an internal balance is therefore maintained - If a physiological condition moves outside of tolerance limits, the disease will occur as a consequence - organisms must be able to monitor their environment, as both the internal and external are constantly changing homeostasis: the maintenance of a stable/constant (normal) environment despite internal or external changes in the environment, mediated by feedback systems - involves a stimulus-response model in which change in the condition of the external or internal environment is detected and appropriate responses occur via negative feedback: - Detection of the stimulus (input) involves changes in chemical molecules within the individual cell or in animals - picked up by a sense organ (receptor). A chemical message is then transmitted to a coordinating centre (the regulator eg. brain) that determines if a change is required. If so, another chemical message brings about a response (output). The response is again a change in chemicals within a single cell or within an effector organ. Effectors can be either a muscle (with a movement response) or a gland (which will secrete molecules) - a change which reverses a particular trend External changes: - the temperature of surrounding too low/high - responses to danger/potential injury - detecting external stimuli such as pain Internal changes: - stress (cortisol/adrenalin) - change in O2 or CO2 (hyperventilating) - pathogens - nutrient supply levels (diet) - salt/water balance (dehydration) - temperature (fever)

*understand homeothermy as an adaptation to permit homeostasis in a wider range of terrestrial environments [chapter 10]

Homeothermy is thermoregulation that maintains a stable internal body temperature regardless of external influence - homeothermic: the ability to maintain a relatively constant body temperature that is independent of the temperature of the surrounding environment - homeotherm an animal that maintains a relatively constant body temperature that-is independent of the temperature of the surrounding environment

recall that the function of hormones [chapter 9]

Hormones are chemical messengers (produced mostly in endocrine glands) that relay messages to cells displaying specific receptors for each hormone via the circulatory or lymphatic system. - hormone: a regulatory chemical of the control and coordination system; capable of bringing about a specific response to a particular stimulus - the hypothalamus controls the endocrine system, secretes hormones which act on pituitary gland (the link between nervous and endocrine system) - the pituitary gland is the "master" controls the activity of all endocrine glands by producing more/less of particular hormones - Endocrine hormones travel long distances through the blood supply of animals to reach the target cells that have receptors that are complementary to the shape of the hormone. - The endocrine system is a collection of glands in the body that send messages to other parts of the body - to target cells (via the bloodstream or lymphatic system) by secreting chemicals called hormones eg. insulin targets muscle cells to absorb more glucose from the bloodstream endocrine system (hormone) --> bloodstream --> target cell

analyse the differences and similarities between passive immunity and active immunity for both naturally and artificially acquired immunity [chapter 11]

Immunity: when the body builds up resistance to future attacks by a specific pathogen two types: - passive - active active immunity: - occurs when our own immune system is responsible for protecting us from a pathogen (due to the presence of memory T-cells and B-cells) - this is acquired through natural exposure (natural active) to a pathogen or through the use of vaccines (safe/weakened virus) (artificial active immunity) - lasts a very long time passive immunity: - occurs when we are protected from a pathogen by immunity gained from someone else, usually short-lived - can occur through a mother giving antibodies to a baby via placenta or breast milk (natural passive) or through a serum injection eg. snakebite (artificial passive) - antibodies gained via the placenta and via antibody serum injection

describe the role of stomata and guard cells in controlling the movement of gases (oxygen, carbon dioxide and water vapour) in leaves [chapter 8]

In complex plants, most photosynthesis occurs in one specialised organ, the leaf. The typical leaf consists of a broad, flat part called the lamina, which is joined to the rest of the plant by a stalk or petiole. stomata - pores in leaf epidermis, bound by guard cells; allows gas exchange and transpiration guard cells - control diameter of pores - work together to regulate entry/exist of gases and controls water loss Stomata permit gas exchange between the air and photosynthetic cells inside the leaf. Gas exchange through stomata is associated with water losses. Guard cells help regulate these water losses. Each stoma is bounded by two guard cells regulate the entry/exist of O2, CO2 and water vapour. Guard cells take up water by osmosis (potassium ions) and swell to become turgid (opening the pore). When guard cells lose water and K+ they become flaccid and close. The opening and closing of stomata depend on environmental factors: - stomata open during the day in response to light and close at night - low CO2 levels also promote stomatal opening - conditions that cause water stress cause stomata to close to prevent water lose

Recognise that phagocytosis is a form of endocytosis [chapter 3]

In endocytosis, the membrane may actually engulf particulate matter (phagocytosis) or extracellular fluid and its contents (pinocytosis). phagocytosis - 'cell eating': engulfing of a solid material by a cell through the extension of the cell membrane over it, and formation of a food vacuole - usually occurs during the second line of defence when combating pathogens

explain how glomerular filtration, selective reabsorption and secretion across nephron membranes contribute to the removal of waste [chapter 7]

In kidney's medulla - the nephrons are responsible for the filtration of blood to selectively reabsorb required nutrients and water and secrete unwanted waste molecules in urine 1. Small amounts of blood are filtered to urine 2. Required molecules and water are reabsorbed 3. Unwanted waste molecules are secreted

explain the relationship between photosynthesis and the main tissues of leaves (spongy and palisade mesophyll, epidermis, cuticle and vascular bundles) [chapter 8]

In most leaves, the majority of photosynthesis is carried out in the upper cell layers. epidermis: - a layer of closely fitting, flat cells covers the top and bottom surfaces of the leaf (the epidermis) and protects the inner layers of cells - Allows sunlight to penetrate to all cells; allows CO2 to diffuse in and O2 to diffuse out as quickly as possible - stomata on lower epidermis: Allows CO2 and O2 to diffuse in and out; reduces evaporative water loss cuticle: - thick, waxy cuticle - having leaves covered by a thickened cuticle prevents water loss from the leaf surface. spongy mesophyll: - parenchyma tissue that has many spaces between cells to facilitate the circulation of air and the exchange of gases - air spaces allow H2O, CO2 and O2 to diffuse into and out of all cells palisade mesophyll: - photosynthetic mesophyll cells usually found below the surface of plant leaves - Chloroplasts in palisade cells oriented horizontally to the light rays expose as much chlorophyll as possible to sunlight vascular bundles: - a collection of tube-like tissues that flow through plants, transporting critical substances to various parts of the plant. - Xylem transports water and nutrients, phloem transports organic molecules, and cambium is involved in plant growth.

understand how pathogens (bacterial and viral) can cause both physical and chemical changes in host cells that stimulate the host immune responses (introduction of foreign chemicals via the surface of the pathogen, production of toxins, recognition of self and non-self) [chapter 11]

In order for a pathogen to cause disease, it must first gain entry into the appropriate host cells and then, in most cases, multiply. To do this, it must overcome defences the host has evolved to prevent this. - immune system: a host defence system, comprising many biological structures and processes within an organism, that protects against disease - The body has many defences against a disease that constitute the immune system. There are two parts of the immune system, each of which plays a role in defending the body: 1. the innate immune system 2. the acquired (adaptive) immune system Innate immune system (non-specific to antigens): - the first line of defence - the second line - complement system Acquired (adaptive) immune system (specific to antigens): - humoural response - cell-mediated

Explain how the size of a cell is limited by the relationship between the surface area to volume ratio, and the rate of diffusion [chapter 3]

In order to operate efficiently, cells cannot grow too large. The ratio of surface area to volume decreases with increased size, limiting the rate of diffusion of nutrients into a cell and the removal of wastes out of the cell. It is not possible for a single cell to grow into a large organism. Instead, an organism needs to increase the number of cells and these cells need to be able to hold together and communicate in some way. - cells are small as they need to have a large surface area to volume ratio to allow for fast intake of nutrients (move easily into the cell's centre) and excretion of waste from cells - when cells are too large they struggle to survive

discuss the factors (light, temperature, wind, humidity) that influence the rate of transpiration [chapter 8]

Light - Stomata usually open in the light and close in the dark. - stomata open (gas exchange and transpiration increases) - stomata close (gas exchange and transpiration decreases) Temperature - An increase in temperature increases the rate of transpiration. Humidity - An increase in humidity causes a decrease in transpiration. This is due to a decreased diffusion gradient between the intercellular spaces and the atmosphere, which reduces evaporation. Wind - Wind increases transpiration by the removal of water vapour around the stomatal pore. This maintains a concentration gradient for all gases and water vapour. Soil water - If the supply of soil water is reduced, the solute concentration of the soil will increase. This results in a decrease in the amount of water absorbed by the roots and a decrease in the transpiration rate.

Identify the following structures from an electron micrograph: chloroplast, mitochondria, rough endoplasmic reticulum and lysosome [chapter 3]

Page 80 of the textbook: - chloroplast: chloroplasts are large, consisting of a fluid matrix or stroma and stacks of flattened membranous discs called grana (singular stack = granum). - mitochondria: mitochondria (singular mitochondrion) are cigar-shaped and bound by a double membrane. The inner membrane is folded into cristae, which increase the surface area for attachment of enzymes and their metabolic reactions. The membranes enclose the fluid matrix. - endoplasmic reticulum: endoplasmic reticulum is a network of flattened, membrane-bound sacs called cisternae. - lysosome: A lysosome is a simple spherical sac containing digestive enzymes. Lysosomes can fuse with vesicles or food vacuoles to digest their contents.

*compare the distribution of stomata and guard cells in plants adapted to different environments (aquatic, terrestrial) as an adaptation for osmoregulation in plant tissue [chapter 10]

Plants have evolved adaptations to prevent water loss or to maximise water uptake. Adaptations to reduce transpirational water loss include: - leaves with low surface area to volume ratio - reduced number of stomata - sunken stomata - hairs on the leaf surface - folding of leaf - reduction in the time the stomata are open. Terrestrial plants are defined as any plant that grows on, in or from the land. By contrast, aquatic plants are plants that thrive when their roots are submerged in water. Terrestrial vs Aquatic: Terrestrial plants get plenty of air so they usually have stomata on the bottoms of their leaves. Aquatic plants have their leaves near or under the water, but they also need to breathe. Plants that float on the surface of the water have their stomata on top, where they have access to air.

Compare the structure of prokaryotes and eukaryotes [chapter 3]

Prokaryotes are smaller than eukaryotic cells and have a simpler structure, also they lack distinct membrane-bound organelles and a cytoskeleton. The genetic material is bound into a single circular DNA molecule floating within the cytoplasm, unlike eukaryotes which have multiple chromosomes inside the nucleus.

Recall what prokaryotic cells are [chapter 3]

Prokaryotic organisms, known as prokaryotes, are composed of an extremely small, single-cell contained within a semi-rigid cell wall. There is no compartmentalisation of the cell contents for specific functions. Some have a flagellum to help them move about in their aquatic environment (which may be the body fluids of multicellular organisms). lack internal membrane-bound organelles, do not have a nucleus, are significantly smaller than eukaryotes, usually have a single circular chromosome and exist as single cells

*explain the mechanisms involved in the transport of water and organic nutrients through a vascular plant [chapter 8]

Running through the petiole are vascular bundles containing the xylem (transporting water and mineral ions from the roots) and phloem (transporting sugars and other small organic molecules/nutrients between different parts of the plant).

Explain how the cell membrane maintains relatively stable internal conditions through the process of active transport of a named substance against a concentration gradient [chapter 3]

Various materials must move in and out of cells so that biological activities can take place in the cell. The cell membrane allows some solute molecules or ions, but not others, to move freely through it. It is selectively permeable. Materials move in and out of cells via passive transport or active transport. active transport: the movement of materials into and out of a cell, usually against a concentration or ionic gradient, requiring cellular energy (low to high concentration - ATP energy - larger molecules) endocytosis: the active movement of materials into the cell is termed endocytosis. exocytosis: the active transport of materials out of cells is termed exocytosis. protein channels: used to "pump" molecules against a concentration gradient

understand how stem cells differ from other cells and what their properties are [chapter 5]

Stem cells are unspecialised cells that have the capacity to develop into many different cell types under special conditions, as they can activate any part of their genetic material, unlike specialised cells All stem cells have two main properties: 1. self-renewal: the ability to go through several cell cycles without further differentiation, and 2. potency: the ability to differentiate (change) into specialised cell types - embryonic stem cells - the first ball of cells in an animal (blastula) - adult stem cells - stem cells found in the body after birth are responsible for repair and maintenance of the adult body

Describe the structure of the cell membrane (including protein channels, phospholipids, cholesterol, glycoproteins) based on the fluid mosaic phospholipid bilayer model [chapter 3]

The basic structure of the membrane is a known as a phospholipid bilayer (the main structure of the cell membrane consisting of two layers of phospholipids arranged so that the hydrophilic heads face the internal and external fluid environments). phospholipid: - a molecule that has a negatively charged phosphate 'head' (hydrophilic - good with water) and two fatty acid 'tails' (hydrophobic - hates water) protein channels: a channel passing through the centre of a protein, the lining of which is hydrophilic cholesterol: regulates the fluidity of the membrane so that it is neither too rigid nor too fluid for the functioning of the cell. glycoproteins: a protein with attached polysaccharides that reacts predominantly as a protein, important as recognition features Fluid mosaic model: a description of how molecules are arranged in the cell membrane; 'mosaic' refers to the many different types of molecules (including phospholipids) that make up the structure of the membrane; 'fluid' refers to the constant movement of the phospholipids and other molecules that make up the membrane

Describe how the cell membrane maintains relatively stable internal conditions through the passive movement (diffusion, osmosis) of some substances along a concentration gradient [chapter 3]

The cell membrane is a selectively permeable barrier that controls the movement of substances in and out of the cell (some small substances can diffuse easily eg. water, while larger molecules eg. protein molecules are prevented). The cell maintains a stable internal condition through passive movement, as various materials must move in and out of cells so that biological activities can take place in the cell. The cell membrane allows some solute molecules or ions, but not others, to move freely through it. Passive transport: the movement of materials into and out of a cell without the expenditure of energy (high to low concentration - no energy) The cell membrane and its structure has the following functions: * To help in the active transport of materials in and out of the cell * To provide a certain degree of mechanical support to the cell, so that it can maintain its shape * To act as a receptor for chemical materials (e.g. hormones) and so maintaining the the specificity of the particular cell type.

Predict the direction of movement of materials across cell membranes based on factors such as concentration, physical and chemical nature of the materials [chapter 3]

The cell membrane is a selectively permeable structure that allows the passage of only certain molecules. Diffusion, facilitated diffusion and osmosis are forms of passive transport of materials. Diffusion is the passage of solutes from a hypertonic solution (one of high concentration) to a hypotonic one (one of low concentration) through a selectively permeable membrane. Facilitated diffusion is the transport of substrate molecules through the membrane by special enzyme-like carrier molecules. Osmosis is the passage of the solvent (water) from a hypotonic to a hypertonic solution through a selectively permeable membrane that is impermeable to the solutes in this solution.

Summarise the process of photosynthesis in terms of the light-dependent reactions and light-independent reactions [chapter 4]

The chloroplast is a cell organelle with two membranes. Light dependant: Small flattened disc-shaped membrane sacs (thylakoids), stacks called grana contain the chlorophyll which captures the light energy. - chemical reactions in the chloroplast, involving excitation of chlorophyll electrons by energy transfer from specific wavelengths of light and resulting in the splitting of water to release hydrogen for the light-independent reactions and formation of ATP Light independent: Occurs in the stroma that is enclosed by these membranes is a watery mixture of different chemicals to that of the cytoplasm. Carbon from carbon dioxide is 'fixed' into organic compounds. - the second stage of photosynthesis, in which carbon dioxide is reduced by the hydrogen formed in the light-dependent reactions, with the input of energy from ATP, to form glucose; these reactions do not need the presence of light (Calvin-Benson cycle is the cyclic reactions of the light-independent phase of photosynthesis)

Recall that organisms obtain the energy needed to recycle Adenosine Triphosphate (ATP) from glucose molecules in the process of cellular respiration [chapter 2]

The energy released at one site of a cell is often required at another site. This is very important in all metabolic reactions such as photosynthesis and cellular respiration. In biological systems, special molecules are used to transport the energy from place to place, or simply to store it in a readily accessible form. Adenosine triphosphate (ATP) is the major molecule involved in this process. Adenosine triphosphate (ATP) is the major molecule in living organisms involved in storing energy in a readily available form and transferring it from one site to another. Organisms obtain the energy needed to recycle adenosine triphosphate (ATP) from glucose molecules in the process of cellular respiration. ATP consists of the nitrogen base adenine, the ribose sugar and three phosphate groups, arranged in sequence. New ATP is formed from ADP and phosphate if sufficient energy is available.

explain how the leaf facilitates that gas exchange (oxygen, carbon dioxide and water vapour) in plants [chapter 8]

The leaf epidermis of angiosperms is covered with tiny pores called stomata. Angiosperms have air spaces between the cells of the stems, leaves and roots that are continuous to allows gases to move freely through them into the plant's cells via stomata. Gases enter the leaf through the stomata, inside the leaf are large air spaces and loose arrangement of the spongy mesophyll facilitate the diffusion of gases and provide large surface area for gas exchanges (net consumption of carbon dioxide and oxygen produced in excess which diffuses out of the leaf when photosynthesising - opposite when just respiring in the dark).

Demonstrate the relationship between the light-dependent reactions and light-independent reactions [chapter 4]

The light dependant is the first phase of photosynthesis and creates the NADPH and ATP needed for the light-independent phase to fixate carbon to synthesise glucose for plant cell's nutrients. Light-dependant: 1. light energy is absorbed by chlorophyll and thylakoid membrane 2. water molecules split into oxygen, H+ and electrons 3. NADP receives H+ electrons to form NADPH 4. NADPH produces ATP 5. Oxygen molecules are released from chloroplasts Light-independent: 1. NADPH from the light phase provides hydrogens 2. ATP from the light phase provides energy 3. CO2 is fixated through a series of reactions to form glucose

make decisions and justify them in regard to best practice for the prevention of disease outbreaks based on the critical analysis of relevant and current information [chapter 12]

The most effective method of prevention of disease transmission, if it is a vaccine-preventable disease, is a vaccine. This artificially acquired immunity is the most effective as it lasts forever. Most effective strategies when diseases outbreak without vaccines - personal hygiene, contact tracing (tracing cases back to their original source), quarantine, reduction of mass gatherings (limit number of people in one space), travel restrictions (limits global spread).

evaluate strategies to control the spread of disease personal hygiene measures community level: contact tracing and quarantine, school and workplace closures, reduction of mass gatherings, temperature screening and travel restrictions [chapter 12]

The spread of disease can be controlled through the concepts of: 1. hygiene - regular hand washing with soap, sneezing into elbow etc. - decreases the risk of transmission - virus is broken down with soap, sneezing into elbow reduces potential droplet transmission 2. vaccination - vaccination is a highly effective method of preventing certain infectious diseases. Vaccines are generally very safe, and serious adverse reactions are uncommon. Routine immunisation programmes protect most of the world's children from a number of infectious diseases that previously caused millions of deaths each year. For travellers, vaccination offers the possibility of avoiding some infectious diseases that may be encountered abroad. 3. social distancing - in public health, social distancing, also called physical distancing, is a set of non-pharmaceutical interventions or measures intended to prevent the spread of a contagious disease by maintaining a physical distance between people and reducing the number of times people come into close contact with each other (1.5 metres) 4. herd immunity - the resistance to the spread of a contagious disease within a population that results if a sufficiently high proportion of individuals are immune to the disease, especially through vaccination (contagious diseases) - important for when people for some reason can't get the vaccine (health reasons) - protects them 5. quarantine - a strict isolation imposed to prevent the spread of diseases (ensures healthy people aren't being exposed and infected people aren't let out into the general population)

Identify the removal of wastes from cells [chapter 2]

To maintain its internal environment, the cell must be physically separated from the environment and still able to take in nutrients and remove waste. Examples: Carbon dioxide: removed through respiration Oxygen: waste product of plants Urea: removed in urine Ammonia: removed in urine Uric Acid: removed in urine Water: removed in urine + sweat + the kidney Ions: removed in the kidney Metabolic Heat: removed in sweat

Explain how energy is transported in cells [chapter 3]

To move substances against a concentration or electrochemical gradient, a cell must use energy. Primary active transport directly uses a source of chemical energy (e.g., ATP) to move molecules across a membrane against their gradient.

*Contrast and compare processes of diffusion, osmosis, and active transport, with reference to the structure and function of the cell membrane [chapter 3]

Various materials must move in and out of cells so that biological activities can take place in the cell. The cell membrane (allows some solute molecules or ions, but not others), to move freely through it. It is selectively permeable - phospholipid bilayer. Materials move in and out of cells via passive transport or active transport - protein channels: used to "pump" molecules against a concentration gradient passive: the movement of materials into and out of a cell without the expenditure of energy - diffusion: the process by which molecules or ions of liquids or gases tend to spread out from regions of their higher concentration to regions of their lower concentration (simple is the free and unaided, facilitated is the passive movement of molecules loosely bound to carrier molecules) - osmosis: the movement of water from a region of low solute concentration to a region of high solute concentration through a selectively permeable membrane to counteract the differences in solute concentration (solutions - hypertonic, hypotonic, isotonic) active: the movement of materials into and out of a cell, usually against a concentration or ionic gradient, requiring cellular energy. Energy is required because the substance must be moved against its natural tendency to diffuse in the opposite direction. Movement is unidirectional. In contrast, diffusion is reversible, depending on the direction of the concentration gradient. eg. endocytosis (active movement of materials into the cell) and exocytosis (active transport of materials out of cells) - concentration gradient: a difference in the concentration of a solution at two different points, e.g. across a barrier such as a cell membrane

identify and explain the various mechanisms that maintain water balance in plants in terms of structural features and homeostatic mechanisms - consider xerophytes, hydrophytes, halophytes and mesophytes in responses [chapter 10]

Water loss from the plant by evaporation from its surfaces is called transpiration. Unless this water is continually replaced, the stomatal guard cells will collapse, and the stomata will close, preventing further diffusion of carbon dioxide into the leaf. Structural features: - stomata (each stoma is surrounded by two guard cells, the opening and closing of stomata involve variations in the water content of the guard cells - open increases water loss (turgid) and closed decreases water loss (flaccid)) - vacuoles (when a waste product is water, its function is to maintain the balance of water inside and outside a cell) - cuticle (the epidermal cells often secrete a waxy cuticle reduces evaporation of water from the cells) Homeostatic mechanisms: - abscisic acid (plant hormone (ABA) produced in response to drought conditions and reduces transpiration by closing the stomata - prevents water loss) Xerophytes: a plant that has adaptations to survive in an environment with little liquid water Hydrophytes: any plant adapted to grow wholly or partly submerged in water or wet habitats Halophytes: a plant that grows in waters of high salinity (salt content) Mesophytes: a plant adapted to growing in well-watered soil

recognise the different types of nitrogenous wastes produced by the breakdown of proteins [chapter 7]

When cells break down proteins, they produce nitrogenous wastes, such as ammonia, urea. The excretory system serves to remove these nitrogenous waste products, as well as excess salts and water, from the body. excretion - the removal of metabolic wastes from the body ammonia - an inorganic nitrogen compound; in animals, a toxic product of the breakdown of excess amino acids urea - a water-soluble nitrogenous excretory product of protein breakdown uric acid - a complex non-toxic nitrogenous excretory product that is only slightly soluble; present in waste in reptiles and birds

describe and contrast the structure and function of xylem and phloem tissue (sieve tubes, sieve plates, companion cells) [chapter 8]

Xylem - water and mineral ion transport (dead to provide maximum volume for water - no organelles) - principal water-conducting tissue in vascular plants a complex tissue composed of living and dead cells; the tracheids and vessels are the non-living components through which water and dissolved mineral nutrients pass from the roots to the leaves in the transpiration stream Phloem - transport of organic nutrients (living - uses energy) - principal food (sugar) conducting tissue in vascular plants a complex tissue composed of living and dead cells; its functional unit consists of a sieve element and a companion cell. Sieve tubes (composed of sieve elements end-to-end) provide the route for the movement of organic solutes in vascular plants - the bulk of tissue is sieve tubes and plates and their companion cells (tiny holes in the tube allow sugar solution to pass through the plant) - sieve tubes are conducting cells, companion cells control metabolism and load/unload sugar into sieve tubes

explain the adaptive immune responses in vertebrates — humoral (production of antibodies by B lymphocytes) and cell-mediated (T lymphocytes) — and recognise that memory cells are produced in both situations [chapter 11]

acquired (adaptive) immune system: immunity that is not present at birth but is 'learned'; the learning process starts when a person's immune system encounters foreign invaders and recognises non-self substances (antigens) - the system then generates special chemicals (antibodies) that neutralise the pathogen The acquired immune system distinguishes two groups of foreign substances: 1. antigens: molecules on the surface of viruses and foreign cells (humoral) 2. self cells that display abnormal MHC self-marker proteins (from antigens that have been engulfed and broken down) (cell-mediated) Humoral response (extracellular - antibodies): 1. Pathogens that are present in the bodily fluids of the host (blood/liquids/fluids in the body outside cells) 2. Antigens (of the pathogen) are recognised by B-cells through special receptors 3. The B-cells start to multiply into many plasma cells and few memory B-cells 4. The plasma cells are antibody "factories" that produce many antibodies specific to a certain antigen 5. The memory B-cells remember the antigen so that any future infections are dealt with faster (immunity) ways antibodies destroy an antigen: - neutralisation - agglutination - precipitation - complement activation Cell-mediated response (intracellular): 1. Pathogens that are present inside host cells the have survived phagocytosis 2. The host cell presents the antigen with the help of MHC II proteins 3. T-cells (stored in the thyroid), recognises the presented antigens 4. They release lymphokines to alert macrophages 5. Assist in the apoptosis (cell death) of the invaded cell 6. Some T-cells become memory T-cells to build immunity Humoral: - occurs in blood/fluids - antigens found in body fluids - immune cell involved - B-cell - the mechanism used to destroy pathogen - antibodies - it is a specific response as B cells have specific receptors for specific antigens - this response leads to memory B cells Cell-mediated: - occurs inside white blood cells - antigens found in immune cells (macrophages) - immune cell involved - T-cell - the mechanism used to destroy pathogen - apoptosis (cell death) - it is a specific response as it targets specific cells which are infected with antigens - this response leads to memory T cells

Describe the structure and role of the active site of an enzyme [chapter 2]

active site - the portion of an enzyme in contact with the substrate; at this point, it will have a specific shape which corresponds to the shape of at least a portion of the substrate molecule (it is the "lock") Structure: The overall action of enzymes can be explained by the 'lock and key' hypothesis which suggests the enzymes' function relies on its shape. Each enzyme is made up of a long chain of amino acids which are folded uniquely into 'glob' shapes. The shape of an enzyme is complementary to the shape of the substrate and they attach together as a 'lock and key'. The portion of the enzyme in contact with the substrate is called the active site. Role: When an enzyme-substrate complex is formed, it is 'activated' into forming the products of the reaction. Once the product is formed, the product molecule no longer fits into the active site. It then escapes into the surrounding allowing the active site to receive a further substrate molecule.

recognise that multicellular organisms have a hierarchical structural organisation [chapter 5]

cells: - Cells of multicellular organisms must stay together. tissues: - Tissues are composed of cells of one type that are differentiated for a particular function (e.g. cardiac muscle) - four types - connective, epithelial, muscle, nervous organs: - Organs are functional, and structural units made up of more than one type of tissue (e.g. the heart, stomach, brain, skin) systems: - A system comprises different organs working together for one main function (e.g. the vascular system, digestive, nervous) * Plants have tissues arranged in organs, e.g. the leaf, and two systems (the root and shoot).

Recognise what cellular respiration is and how the reaction sequence known as aerobic respiration works [chapter 4]

cellular respiration is an enzyme-controlled series of chemical reactions - cellular respiration is the breakdown of glucose in cells to release energy; may occur with (aerobic) or without (anaerobic) oxygen - Cellular respiration may occur either in the presence of oxygen (aerobic cellular respiration) or in the absence of oxygen (anaerobic cellular respiration) - aerobic respiration (glycolysis, Krebs cycle and electron transfer chain) requires oxygen mitochondrion: a membrane-bound cellular organelle; has inner membrane forming folds (cristae) on which are found enzymes for aerobic respiration, and a fluid matrix glycolysis: the first stage in cellular respiration; occurs in the cytoplasm; does not require oxygen Krebs cycle: the cyclic series of chemical reactions in mitochondria of cells in which citric acid and water releases carbon dioxide molecules as waste and hydrogen atoms electron transport chain: a series of coenzymes along which high-energy electrons pass to release energy to form ATP (the final stage in aerobic cellular respiration in which most ATP molecules are formed) glycolysis: the first stage in cellular respiration; occurs in the cytoplasm and results in the gain of 2 ATP and 2 pyruvate molecules; does not require oxygen - with an undersupply of oxygen, ATP is produced from glucose by the reaction sequence known as anaerobic respiration (glycolysis with 'fermentation') Respiration: Reactants - C6H12O6 (glucose) + 6O2 (oxygen) Products - 6H2O (water) + 6CO2 (carbon dioxide) Occurs - Mitochondria Energy - Released Equation - C6H12O6 + 6O2 -------> 6CO2 + 6H2O Purpose: convert solar energy into chemical energy and then store that chemical energy for future use. Organism: Animals

interpret data for the modelling of the spread of disease using secondary data or computer simulations [chapter 12]

data analysis: - correlation (strong/weak, positive/negative) - p value (statistical significance) - measures of central tendency - mean, median, mode - measures of spread - standard deviation

identify the difference between infectious diseases and non-infectious diseases [chapter 11]

disease: an abnormal condition of an organism which interrupts the normal bodily functions pathogen: a microorganism that causes disease infectious: able to be passed from one individual to another - invasion by a pathogen and can be transmitted from one host to another Infectious diseases are caused by pathogens (a biological agent that causes disease or illness to its host) eg. measles, COVID-19, aids - contagious - passed from person to person (flue, corona, aids) - non-contagious (requires a vector to pass on the pathogen) eg. malaria - mosquitos - endemic (constantly present), epidemic (multiple cases in a specific area), pandemic (worldwide) non-infectious: cannot be passed from individual to individual - genetic and lifestyle diseases Non-infectious diseases are diseases that cannot be spread. There are many causes of such diseases: - malfunctioning - inherited condition - genetic disease - environmental condition - nutritional disease eg. cancer, hay fever, malnutrition, alcoholism, osteoporosis

Understand what endocytosis is [chapter 3]

endocytosis is a form of active transport that usually moves large polar molecules that cannot pass through the hydrophobic cell membrane into the cell via passive transport

*describe how the cell types and structures that make up a leaf contribute to efficient photosynthesis [chapter 8]

epidermis: - a layer of closely fitting, flat cells covers the top and bottom surfaces of the leaf (the epidermis) and protects the inner layers of cells - Allows sunlight to penetrate to all cells; allows CO2 to diffuse in and O2 to diffuse out as quickly as possible - stomata on lower epidermis: Allows CO2 and O2 to diffuse in and out; reduces evaporative water loss cuticle: - thick, waxy cuticle - having leaves covered by a thickened cuticle prevents water loss from the leaf surface. spongy mesophyll: - parenchyma tissue that has many spaces between cells to facilitate the circulation of air and the exchange of gases - air spaces allow H2O, CO2 and O2 to diffuse into and out of all cells palisade mesophyll: - photosynthetic mesophyll cells usually found below the surface of plant leaves - Chloroplasts in palisade cells oriented horizontally to the light rays expose as much chlorophyll as possible to sunlight

Summarise the reactions of aerobic respiration by the chemical equation [chapter 4]

glucose + oxygen --> carbon dioxide + water + energy C6H12O6 + 6O2 → 6CO2 + 6H2O + 36-38 ATP

recall that the innate immune response in vertebrates comprises surface barriers, inflammation and the complement system [chapter 11]

innate immune system: the system of non- specific defence mechanisms that include physical barriers such as skin, chemicals in the blood, and white blood cells that attack foreign cells in the body. THE FIRST LINE OF DEFENCE - surface (physical and chemical) barriers: - for a pathogen to infect, has to get through the first line of defence Physical barriers: 1. skin - tough, physical barrier - the dry outer layer of cells inhibits bacterial growth - oil and sweat glands produce anti-bacterial substances - beneficial (good) bacteria live off the oil secreted by sebaceous (oil) glands and destroys pathogen growth 2. mucus membranes - any opening is an opportunity for infection (eyes, mouth (digestive system), nose, urinary system) - openings are lined with moist mucus membranes - pathogens get caught in mucus, which is coughed up or swallowed (removed) - some contain antibodies to prevent pathogens attaching - harmless microbes produce substances that inhibit growth and entry of pathogens. 3. cilia - hair-like structures in airways - move mucus-containing pathogens out of the lungs Chemical barriers: 4. digestive system - conditions unfavourable for pathogens - saliva contains chemicals to destroy microbes (digestive enzymes - mouth) - stomach acid is intolerable to many pathogens (acidic conditions - stomach) - other pathogens cannot tolerate the basicity of the intestines (alkaline - intestines) 5. Urinary and vaginal tracts - Acidic conditions inhibit growth and entry of pathogens - Urine flushes out pathogens (acidity prevents the growth of pathogens - flushes and cleans the urinary system) 6. Tears - wash pathogens away from the eyes THE SECOND LINE OF DEFENCE - inflammatory response - complement system supports

understand that metabolism describes all of the chemical reactions involved in sustaining life and is either catabolic or anabolic [chapter 9]

metabolism - the chemical processes (reactions) occurring within the cells of a living organism to maintain lives catabolic reaction - a chemical reaction in which large molecules are broken down into smaller ones, usually accompanied by the release of energy anabolic reaction - a chemical reaction in which large molecules are built up, usually with a net input of energy catabolic reaction + anabolic reaction = metabolism

recognise that stem cells differentiate into specialised cells to form tissues and organs in multicellular organisms [chapter 5]

multicellular organism - an organism composed of many integrated cells specialised cells - cell differentiation is the process by which a cell becomes specialised in a multicellular organism in order to perform a specific function cell specialisation - the changes in a cell that allow it to perform a specific function

discriminate between a sensory neuron and a motor neuron (consider dendrites, soma, body, axon, myelin sheath, nodes of Ranvier, axon terminal and synapse) [chapter 9]

neurons associated with stimuli are termed sensory (afferent) neurons, whereas motor (efferent) neurons bring about a response sensory (afferent) neuron - a nerve cell which carries information from a receptor to the central nervous system - carries the signal from receptors to CNS motor (efferent) neuron - a nerve cell which transmits information from the central nervous system to an effector organ - carries the signal from PNS to receptor muscles association neuron (interneuron) - the nerve cell within the central nervous system which relays information between sensory input and motor output - transmits impulses between other neurons in the CNS (reflex arc - receives from sensory and relays to motor) dendrites: receives and conducts chemical messages to the cell body so it can function soma: cell body, contains nucleus and controls metabolism (functions) of the cell axon: conducts electrical impulse away from the cell body myelin sheath: insulating layer which allows impulses to transmit quickly - Schwann cells - support regeneration (a type of glial cell) nodes of Ranvier: allows ions to diffuse in and out to pass signal down the axon axon terminal/terminal buttons: send the signal to other neurons

explain the function of each of the sections of the nephron and its function in the production of urine [chapter 7]

osmoregulation - the physiological regulation of water and salt concentrations within the body (homeostasis of water) - Within the kidney, there are pyramids made up of thousands of nephrons (a nephron is the functional unit of the kidney - filter) Step 1 - Bowman's capsule: - blood pressure in the glomerulus (the capillary knot found in Bowman's capsule) pushes fluid containing waste, nutrients and water into Bowman's capsule (ultrafiltration of the blood occurs) Step 2 - Proximal convoluted tubule: - filtrate travels into proximal convoluted tubule and nutrients (glucose, sodium chloride and water) are reabsorbed into the blood Step 3 - Descending Limb of the Loop of Henle: - only permeable to water - diffused out of the filtrate (back into the blood) on the descending part (water reabsorption and increased urine concentrate) Step 4 - Ascending Limb of the Loop of Henle: - only permeable to salts, salts leave the filtrate in the blood (sodium) loop of Henle: high salt concentration in the tissue fluid is maintained, resulting in diffusion of water from the filtrate to the surrounding blood capillaries Step 5 - Distal convoluted tubule: - responsible for the reabsorption of sodium, potassium (K salts), phosphate and calcium ions under the control of hormones Step 6 - Collecting ducts: - filtrate (urine) empties into collecting ducts and moves toward the bladder via the ureter

identify and explain the various homeostatic mechanisms that maintain water balance in animals (osmoregulators and osmoconformers) [chapter 10]

osmoregulation: maintenance of constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations, facilitated by: - osmoregulation - the maintenance of a constant solute and water balance - excretion - removal of metabolic waste material osmoconformer: a marine organism that maintains an internal environment that is isotonic with its external environment osmoregulator: an organism that actively controls internal salt concentrations independently of the salt concentrations in the environment - structural features (excretory system, behavioural responses, physiological mechanisms) homeostatic mechanisms: - antidiuretic hormone (ADH) and the kidney - osmoreceptors cells in the hypothalamus detect when water levels (pressure) in the blood and surrounding tissues are low (more water content = more pressure in the blood, low water = low pressure) - this stimulates the pituitary gland to increase/decrease secretion of the ADH hormone - carried through the blood to the kidneys where it increases the permeability of distal convoluted tubules to increase the level of water absorbed until normal water balance is attained low water: - dehydrated, more water reabsorbed - less water in urine (darker) - low osmotic pressure in the hypothalamus high water: - hydrated - less ADH released - less water reabsorbed - more water in urine (clearer) - high osmotic pressure

describe the following virulence factors that aid in pathogenesis: adherence factors, invasion factors, colonisation factors, toxins, lifecycle changes and immune response blockers [chapter 11]

pathogenesis = developing a disease virulence = the ability of a pathogen to cause disease virulent factor = a molecule that can contribute to the survival of the pathogen 1. Adherence factors - pathogens must adhere (stick) to a molecule on the membrane of the host cell to all it to penetrate tissues and colonise the host - when a molecule uses special glycoprotein molecules (adhesions) to attach to the host cell's receptors (specific lock and key) 2. Invasion factors - protein that allows pathogens to enter cells - they produce proteins that either disrupt host cell membranes or stimulate endocytosis into the host cells 3. Colonisation factors - proteins that help the pathogen colonise (settle) and survive (community) - put up with harsh conditions 4. Toxins - molecules that cause disease or tissue damage two types: - exotoxins - proteins produced inside pathogenic bacteria are secreted (produced and released) - endotoxins - lipids part of the outer membrane (liberated when the cell wall breaks) 5. Lifecycle changes - pathogens will have a life cycle with different stages, each with different surface molecules, to help them colonise their host - the host's immune system has difficulty in recognising these, enabling the survival of the pathogen 6. Immune response blockers - a protective pathogenic layer is formed around the pathogen (biofilm) which protects it from the host's immune response

*illustrate the stimulus-response model with examples of receptors, sensory & motor neurons, effectors [chapter 9]

reflex arc - sensory neurons detect changes in stimuli and take this signal to the interneurons in the spinal cord, which then relay the information to motor neurons which make effector muscles initiate a response

Recall what the process of photosynthesis is and the overall process can be summarised into a balanced chemical equation [chapter 4]

photosynthesis is an enzyme-controlled series of chemical reactions that occurs in the chloroplast (green chlorophyll pigment) in plant cells and uses light energy to synthesise organic compounds (glucose), and the overall process can be summarised in a balanced chemical equation: carbon dioxide + water glucose + oxygen + water 6CO2 + 12H2O → C6H12O6 + 6O2 + 6H2O Photosynthesis: Reactants - 6H2O (water) + 6CO2 (carbon dioxide) Products - C6H12O6 (glucose) + 6O2 (oxygen) Occurs - Chloroplasts Energy - Absorbed Equation - 6CO2 + 6H2O -------> C6H12O6 + 6O2 Purpose: provide cells with the energy they need to function. Organism: Plants

identify the following pathogens: prions, viruses, bacteria, fungi, protists and parasites [chapter 11]

prions: - an abnormal form of a normally harmless protein - non-living, fatal - proteins that cause other proteins to fold incorrectly and cause tissue damage/cell death eg. linked to neural (brain disease) like "mad cow" viruses: - non-living protein capsules containing DNA - requires a host cell to reproduce - can be prevented using a vaccine * life cycle of a virus - attack host cell and inject DNA (protein coat remains outside), viral nucleic acid replicates within the cell, new protein coat formed within the host cell, new viruses assembled, host cell bursts (lysis) and viruses are released to infect other cells eg. coronavirus bacteria: - unicellular, prokaryotic organisms - most are harmless and treated with antibiotic - pathogenic bacteria release toxins or damage the tissue in their host cells eg. coccus, bacillus, spirillum, vibrio. fungi: - eukaryotic heterotrophs - uses hyphae (similar to roots) to absorb nutrients from the host eg. athletes foot, ringworm protists/protozoa: - unicellular eukaryotes - usually spread by contaminated water (and kissing) - causes infection of the intestinal tract parasites: -an organism that lives in or on another organism (host) and derives its nourishment from it - requires host cell for nutrients - endoparasites (live inside host eg. tapeworm) - ectoparasites (live on the skin of host eg. fleas)

explain the relationship between the structural features and function of gaseous exchange surfaces (as well as similarities between alveoli and gills) in terms of exchange of gases [chapter 6]

structure (capillary, alveoli and villi): - large surface area for maximum gas absorption - moist to dissolve ions - one or two cells thick for easy gas exchange/transfer - surrounded by many capillaries for maximum gas exposure function: - oxygen in, carbon dioxide out * capillary bed throughout the body - provides O2, removes CO2 * alveoli in the lungs - removes CO2, provides O2 - the alveoli are surrounded by capillaries that allow oxygen to pass from the alveoli into the blood - oxygen moves by diffusion (high to low) from the air in alveoli into the blood - carbon dioxide into the alveoli from the blood fish gills and alveoli: - In fish, gaseous exchange takes place between the water and gills which has many blood vessels - Blood flowing through the gills takes oxygen from the water and releases carbon dioxide into the water - Oxygen diffuses from the water into the filament capillaries along a concentration gradient, and carbon dioxide diffuses in the opposite direction Structure and function: - Filaments in gills have a large surface area and many are stacked in order to increase the amount of water that can flow through for oxygen intake and carbon dioxide release (in blood cells) - Similar to alveoli except alveoli have air, filaments have water to allow oxygen in

Explain how reaction rates of enzymes-driven reactions can be affected by certain factors [chapter 2]

temperature - they are heat-sensitive, working best at an optimum temperature (plants 30°C; human body 37°C) pH - they are pH-sensitive, working only within a narrow range of the optimum pH specific for each enzyme inhibitors - enzymes are inhibited by poisons, which either compete with the normal substrate molecules for the active site (competitive inhibition) or block the active site permanently (non-competitive inhibition) concentration - as the concentration of substrate increases, the rate of enzyme action increases to a maximum limiting value and then plateaus - substrate and enzyme concentration - temperature, pH, the presence of inhibitors, and the concentration of reactants and products

identify and explain the varying thermoregulatory mechanisms of endotherms and how they control heat exchange and metabolic activity [chapter 10]

thermoregulation: the maintenance of a constant internal temperature of an organism independent of the temperature of the environment - ectotherm: any animal whose regulation of body temperature depends on external sources (cold-blooded) - endotherm: an animal that can maintain a constant body temperature independent of the environment (warm-blooded) 1. structural features brown adipose tissue (fat): - abundant in newborns/hibernating animals - increased number of mitochondria per cell - fuel energy - produces heat (thermogenesis/metabolic activity from organs and tissues) insulation: - preventing loss of heat produced by muscles eg. feathers, fur, blubber, goosebumps (trap air layer around skin) 2. behavioural responses kleptothermy: - huddling in groups to hare body heat hibernation: - state of inactivity characterised by low body temperature, slow breathing and heart-rate and low metabolic rate (winter months) eg. bears aestivation: - inactivity and lowered metabolic rate to survive hot/dry weather (summer months) eg. reptiles torpor: - the shorter type of hibernation (less than 24 hours - an altered state of consciousness where the animal is not awake but not fully asleep) 3. physiological mechanisms vasomotor control: - vasoconstriction - cold environment where the body needs to warm up (less blood flow to the skin surface, less heat loss) - vasodilation - when the body needs to cool down (blood vessels dilate so more blood to the skin surface, more heat loss) evaporative heat loss: - heat is removed when water evaporates, the body cools down eg. sweat, panting countercurrent heat exchange (a countercurrent heat exchanger is an arrangement of blood vessels in which heat flows from warmer to cooler blood, usually reducing heat loss): - cold conditions - blood vessels leading to and from extremities of the body and placed close together - cold blood returning to vein picks up heartbeat from arteries 4. homeostatic mechanisms (eg. thyroid hormones and insulin - negative feedback loops) - the hypothalamus receives information from thermoreceptors on the skin which indicate the temperature is too low - it produces thyrotropin-releasing hormone (TRH) - stimulates the pituitary gland to produce thyroid-stimulating hormone - stimulates the thyroid to release thyroxine through the blood - thyroxine travels in the blood to cells - causing metabolism rate to increase - generating more heat to warm the body

explain the transport of products of photosynthesis and some mineral nutrients via translocation in the phloem [chapter 8]

translocation: the movement of organic solutes in the phloem in any direction that occurs in the sieve tubes of the phloem. sieve tube: the element of phloem functioning to transport organic molecules within the plant; consists of thin-walled, elongated living cells arranged in a longitudinal row and forming a connected series by means of perforations in their end walls Molecules (sugars, amino acids, etc.) produced in the photosynthetic cells of the leaf must be transported to the non- photosynthetic cells of the plant, particularly to actively growing points such as the apex, branches and root tips.