Biology Paper Two
What are indicators of water pollution?
.Bloodworms and sludgeworms can live in water that contains little oxygen. So they are found in polluted water .Stonefly larvae (young stonefly), some mayflies and caddisflies can only live in water that contains a lot of oxygen - so they are indicators of unpolluted water
What effect does carbon dioxide have on photosynthesis?
.CO2 is a limiting factor because it increases the rate of photosynthesis. There is more CO2 to use to make sugars .Once CO2 concentration is high, another factor is limiting the rate of photosynthesis. There is more CO2 to use to make sugars
What are the reasons for maintaining biodiversity?
.Moral reasons: Humans should respect other living organisms .Aesthetic reasons: People enjoy seeing the variety of living organisms that live in different habitats .Ecosystem structure: Some organisms have an important role in ecosystems, such as microorganisms in decay processes and nutrient recycling. If this planet loses species, food chains become more unstable .Usefulness: Some species are particularly useful to humans , for example plants that produce life-saving drugs, or wild varieties of plants grown for crops (as a source of genes if the environment changes).
Name the main endocrine glands in the body?
.Pituitary gland - secretes TSH (thyroid stimulating hormone), ADH ( antidiuretic hormone) and LH (luteinising hormone) .thyroid - secretes thyroxine .pancreas - secretes insulin and glucagon .testis - secretes testosterone .ovaries - secretes oestrogen and progesterone .adrenal - secretes adrenalin .hypothalamous - produces hormones such as TRH (thyrotropin-releasing hormone) and CRH (corticotropin-releasing hormone)
What are indicators of air pollution?
.Some species of lichen can only grow where there is no pollution. Other species can grow where there is air pollution. So, the species of lichen growing on trees can tell you if the air has been polluted .Blackspot is a fungus the infects roses. The fungus is damaged by the sulfur dioxide in the air. So where there is air pollution, the roses are clear of fungus
What effect does temperature have on the rate of photosynthesis?
.Temperature is a limiting factor because it increases the kinetic energy of molecules and increases the rate of enzyme activity making photosynthesis faster .If the temperature is too high, enzymes start to denature and the rate of photosynthesis slows down
Give examples of plant hormones?
.auxins .gibberellins .ethene
How are some common substances exchanged in the body?
.oxygen is needed for respiration an so is exchanged along side carbon dioxide, a waste product of metabolism, in the alveoli of lungs .water is exchanged in the nephrons of the kidney in order to supply cells with enough water to function properly. .both dissolved food molecules, needed for respiration, ans mineral ions, needed for cells to function properly, are exchanged in the small intestine whilst urea, a waste product of metabolism, is exchanged in the kidney
What are the levels of organisation in an ecosystem?
1) An ORGANISM is a single living individual 2) A POPULATION is all the organisms of the same species in an area 3) A COMMUNITY is all the populations in an area 4) A ECOSYSTEM is all the living organisms (the community) and the non-living components in an area All organisms in an ecosystem are dependant on other organisms for food, shelter and so on
What are the advantages of anaerobic respiration?
1) Anaerobic respiration is useful for muscle cells because it can release energy to allow muscles to contract when the heart and lungs cannot deliver oxygen and glucose fast enough for aerobic respiration 2) Respiration can continue in organisms that have no, or very limited oxygen supply
What are the disadvantages of anaerobic respiration?
1) Anaerobic respiration releases much less energy from each molecule of glucose than aerobic respiration 2) Lactic acid is not removed from the body. It builds up in muscle and blood, and must be broken down after exercise
How does blood circulate through the heart?
1) Blood enters the atria 2) The atria contract forcing blood into the ventricles 3) The ventricles contract, forcing blood into the arteries 4) Blood flows through arteries to the organs and returns to the heart through veins.
What are the stages of the transpiration stream?
1) Causes water to enter the roots through osmosis 2) Draws water up the stem through the xylem from the roots 3) Draws water out of the leaf cells and xylem 4) Water vapour evaporates from the leaves mainly through the stomata
How do we use energy released by respiration?
1) In animals: . for metabolic processes to build larger molecules from smaller ones, e.g. proteins from amino acids, large carbohydrates(e.g. starch, glycogen) from small sugars (e.g. glucose), fats from fatty acids and glycerol . to enable muscle contraction . in birds and mammals, also to maintain a constant body temperature in colder surroundings 2) In plants: . to build larger molecules from smaller ones, e.g. sugars, nitrates and other nutrients into amino acids, which are then used to make proteins
What are the effects of increased food demand?
1) Increasing human population means more food is needed 2) The increasing demand for meat and fish means more land is being used for animal farming and a greater impact on wild fish populations - as well as the demand for more food, human activity has had environmental impacts that could reduce the availabilty of land for food production, e.g. global warming, risisng sea levels and increased desertification 3) Movement of people and goods introduces new pests and pathogens to areas, damaging local crops and animals 4) Increased waste is produced, causing more pollution
What is the structure of the urinary system?
1) The renal arteries carry blood from the body to the kidneys 2) The renal veins carry clean blood back to the body 2) The kidneys remove substances including urea from the blood and make urine - urea is produced from the breakdown of excess amino acids in the liver. It is toxic in excess 3) The ureters carry urine from the kidneys to the bladder 4) The bladder stores urine 5) A muscle keeps the exit from the bladder closed until we decide to urinate - urine flows through the urethra to the outside of the body
Describe the functions of leaf adaptations?
1) air surrounds most of the surface of each cell so that gas exchange can take place over most of the surface 2) epidermis cells are transparent to let light pass through to the photosynthetic cells 3) Waxy cuticle is transparent to let light through 4) flattened shape of leaf gives large surface area 5) the mesophyll cells are packed with chloroplasts for maximum photosynthesis 6) xylem cells bring water for photosynthesis 7) phloem removes the sugars made in photosynthesis 8) internal air spaces increase surface area for diffusion of gases 9) stomata (pores) allow carbon dioxide from air into leaf and allow oxygen from photosynthesis to leave leaf
What should a graph showing the rate of change in pH and light intensity look like?
A grpah using light intensity should show that rate of change in pH is directly proportional to light intensity.You could also calculate the inverse square distances and draw a graph to show the relationship of that with rate of pH change. This should show that the rate of change in pH is inversely proportional to distance from the lamp
Give details of a permanent treatment of kidney failure?
A healthy organ, such as a kidney, may be donated by a donor, which is transplanted into the patient. Once the defective kidney is removed. a healthy kidney is connected to the blood circulation, to do the work of diseased kidneys however, this brings about an issue, as the antigens on the transplanted kidney cells are different from antigens on cells in the patient's body therefore, the antibodies in the patient's system will recognise the transplanted kidney as foreign and reject it To prevent this from occuring, the anigens on the transplanted kidney must be as similar in type as possible; the patient must be treated for life with drugs to reduce the effects of the immune system however, this means the patient may get more infections than normal
What is meant by paratism?
A parasite feeds on another organism (the host) while they are living together. This harms the host but benefits the parasite. For example: .A flea feeds by sucking the animal's blood after piercing its skin .Head louse feeds off humans and sucks the blood after piercing the skin on the head .Tapeworms live in an animal's intestines and absorb nutrients from the digested food in the intestine .Mistletoe grows roots into the tree to absorb water and nutrients from the host
What is diabetes?
A person who cannot control their blood glucose concentration properly has a condition known as diabetes. There are two main types of diabetes
How do you calculate BMI?
A person's Body Mass Index (BMI) is calculated using the equation: BMI = weight (kg) / (height(m)) squared
What are pyramids of biomass?
A pyramid of biomass is a diagram that shows the amount of biomass (usually as g/m squared) at each trophic level in an ecosystem. The producer level is the bottom layer, and other levels show the trophic order. The amount of biomass at each trophic level along the food chain gets smaller. This is because some energy at each level is transferred by heating the environment. Food chains are usually no more than 4 or 5 trophic levels long because there is not enough biomass in the top level to provide the energy needed by another trophic level
What are tropisms?
A tropism is a plant's response to a stimulus ( a change in the environment) by growing. A positive tropism is when the plant grows towards the stimulus .Plant shoots show positive phototropism because they grow towards the light .Plant roots show positive gravitropism because the grow downwards - towards the pull of gravity. (Gravitropism is also called geotropism.)
What are effects of adrenalin?
Adrenalin has many targent organs including the liver, the heart and blood vessels. It: .increases heart rate .constricts some blood vessels to make blood pressure higher .dilates other blood vessels to increase blood flow to muscles .causes the liver to convert glycogen to glucose, which is released into the body
What is Adrenalin?
Adrenalin is a hormone that is released from the adrenal glands in response to sudden stress. It brings about the "fight or flight" response
What is aerobic respiration?
Aerobic respiration is a series of chemical reactions that take place mostly inside mitochondria in the cell. This is an exothermic process because it releases energy. This happens continuously in living cells. It is the main source of energy for cells glucose + oxygen --> carbon dioxide + water
What are the differences between aerobic and anaerobic respiration?
Aerobic respiration requires oxygen, releases a lot of energy, completely breaks down glucose and occurs mostly in thr mitochondria whereas, in anaerobic respiration, oxygen is not required and glucose is only partly broken down into lactic acid - releasing much less energy whilst it does not occur in the mitochondria
How are alveoli adapted for their function?
Alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillaries. The lungs are part of the breathing system. The breathing system take air into and out of the body. In the lungs: .oxygen diffuses from the air into the blood .carbon dioxide diffuses from the blood into the air. The lungs are adapted for efficient gas exchange: .millions of tiny alveoli (air sacs) create a large surface area for diffusion of gases .each alveolus is closely associated with a capillary. Their walls are one cell thick, minimising diffusion distance .ventilation of alveolus (breathing) and continual blood flow through capillaries maintains high concentration gradients, to maximise rate of diffusion.
What is anaerobic respiration?
Anaerobic respiration is the incomplete breakdown of glucose to release energy; it occurs in muscle cells and so produces the byproduct of lactic acid and is removed by blood flowing through the muscles and removing it. Unlike aerobic respiration, anaerobic does not and can supply energy to muscles when there is not enough oxygen for aerobic respiration - however, much less energy is produced per molecule of glucose than in aerobic respiration. Extra oxygen is required to oxidise lactic acid to carbon dioxide and water after exercise. In plants and fungal cells, there is a different form of anaerobic respiration that produces ethanol. However, like anaerobic respiration in animals: .it involves the breakdown of glucose .no oxygen is used .less energy is released per glucose molecule
How would you investigate how the change in light intensity from inside a woodland to a nearby open meadow affects where cowslips are growing?
Apparatus: .quadrat .light meter .long measuring tape Method: 1) Set out a measuring tape from inside the woodland out to the open meadow 2) Take a quadrat sample at regular intervals 3) At each quadrat sample, count the number of cowslips, and measure the light intensity - an alternative to counting plants is estimating percentage coverage of the quadrat (e.g. 10%, 50%) by the species. This is useful if it is difficult to count individual plants, or if some plants are much bigger than others. 4) Compare the number of plants with the light intensity along the transect to see how light affects where the plants live Results: You should record results in a table and present them in graph form Conclusion: Cowslips seem to grow better in open meadow because the greater the light intensity the greater the number of cowslips - repeating the transect several times and comparing the results for each transect would help to average out any random variation
Describe the menstrual cycle?
Between puberty and about the age of 50, women have a menstrual cycle that occurs about every twenty eight days. In the first five days of the cycle menstruation occurs, the breaking down of the uterus lining. It begins on day one of the cycle and usually lasts about five days. During the second week, the lining of the uterus is gradually built up. Ovulation is the release of an egg from an ovary, this usually takes place around day 14, therefore days fourteen to sixteen are considered the most fertile period of the month; if fertilisation occurs, the lining of the uterus remains thick so that the embryo can embed into the lining and obtain the nutrients it needs. Alternatively, the lining of the uterus will continue to build up through weeks three and four until day 28 where menstruation occurs and the cycle repeats.
Describe the structure of the kidney
Blood from the renal artery flows into the kindney into the glomerulus, a small knot of capillaries surrounded by the cup-shaped bowman's capsule where filtration of small molecules from blood occurs into the tubule including water, glucose, salts and urea. Selective reabsorption of glucose from the tubule back into the blood, by active transport, occurs at the peak of convoluted tubules - where the tubule is nearest a capillary. The tubule loops back on its self aroud the loop of Henle back into convoluted tubules before reaching a collecting duct where urine containg an excess of urea and water travels to the ureter.
How is blood glucose regulated?
Blood glucose regulation is another example o homeostasis. It is controlled by two hormones: insulin and glucagon. 1) If blood glucose concentration rises, e.g. after a meal the pancreas detects rise in blood glucose concentration; it responds by increasing the secretion of insulin and decreases secretion of glucagon; insulin causes muscle and liver cells to remove glucose from blood and store it as glycogen causing it to fall to normal levels. However 2) If blood glucose concentration falls, e.g after exercise the pancreas detects fall in blood glucoe concentration and so decreases the secretion of insulin and increases secretion of glucagon - glucagon causes liver cells to convert glycogen to glucose and release it into the blood; causing the blood glucose concentration to rise to a normal level
Describe the composition of blood
Blood is made of four main parts: plasma, red blood cells, white blood cells and platelets
Describe the changes in hormones that occur during the menstrual cycle?
Both FSH and LH are secreted from the pituitary gland near the brain. At the beginning of the cycle low levels of progesterone allow FSH to be released - FSH stimulates growth and maturation of follicles in turn the maturing folicles stimulate oestrogen production and this increasing concentration causes thickening of the uterus lining. These high levels of oetrogen stimulate the release of more LH; this surge triggers ovulation causing the corpus luteum to release progesterone - increasing progesterone inhibits FSH and LH release, falling oestrogen and progesterone trigger menstruation.
What is type 1 diabetes?
Cause: The immune system has damaged the person's insulin-secreting pancreatic cells, so the person does not produce insulin Control: They have to inject insulin into the fat below the skin. They have to work out the right amount of insulin to inject so that the blood glucose concentration is kept within safe limits
What is type 2 diabetes?
Cause: The person does produce insulin but their liver and muscle cells have become resistant to it Control: Most people can control their blood glucose concentration by eating foods that contain less sugar, exercising and using medication if needed
What is cellular respiration?
Cellular respiration is a process that releases energy from glucose for use in cellular activities. The main type of cellular respiration is aerobic respiration, which uses oxygen.
What is contraception?
Contraception is the prevention of fertilisation. Hormonal contraception includes hormone pills, implants or injections, andd works by releasing hormones to prevent ovulation and thicken the mucus in the cervix, preventing sperm from passing. Barrier methods include male and female condoms, the diaphragm, caps and sponges. These work by stopping the sperm reaching the egg.
Describe the carbon cycle
Dead organisms that are not broken down by decomposers by decomposers may eventually form fossil fuels, such as coal and oil - when you combust fossil fuels you release the carbon in them back into the air as carbon dioxide; further carbon dioxide is also released into the air through respiration of plants, animals and decomposers. during photosynthesis plants absorb this carbon dioxide gas and convert it into carbon compounds e.g. sugars; carbon compound in plants are passed to animals when they eat the plants, and from animal to animal along a food chain. When these plants and animals die they are broken down by decomposers such as bacteria and fungi - leading to carbon being re-released into the atmosphere in the form of carbon dioxide or being converted into fossil fuels over a period of time - hense the cycle. In the air, carbon is part of carbon dioxide gas. In organisms, it is part of complex carbon compounds. The carbon cycle is important because it recycles the carbon dioxide released in respiration to be taken in by plants in photosynthesis, to make organic molecules in living organisms
What is decay?
Decay is the break down (digestion) of materials by microorganisms
What are the factors that affect distribution?
Factors in the environment affect living organisms and their distribution (how widely spread they are). Changes in these factors may change their distribution. Environmental factors are split into two components: living factors, e.g. prey, competitor and predator and non-living factors such as light, average temperature and rainfall, oxygen levels in water and pollution. Changes in non-living factors can be measured using equipment, e.g. oxygen meter, thermometer, rainfall gauge. For example, temperature affects the rate of reactions and light intensity affects the rate of photosynthesis
What is eutrophication?
Fertilisers added to fields for crops may get into streams and rivers. This adds phosphates and nitrates to the water, which is called eutrophication. Eutrophiocation can lead to the loss of biodiversity in nearby water. 1) Eutrophication causes water plants and algae to grow more quickly 2) Plants and algae cover the water surface, and block light to deeper water 3) Deeper plants cannot get light, so they die 4) Bacteria decompose dying plants and take oxygen from the water 5) There is not enough oxygen left in the water for fish, so they die
How do Fertility drugs works?
Fertility drugs such as clomifene cause an increase in the hormones FSH and LH. The drugs can help women who produce too little FSH by stimulating eggs to mature and then be released.
What is Fick's law?
Fick's law is used to calculate the rate of diffusion. (rate of diffusion is proportional to surface area x concentration difference) /thickness of membrane
What is fish farming?
Fish farming involves growing one kind of fish in an area. The fish are fed and the waste they produce is removed from their tanks however, this process has both advantages and disadvantages. On one hand, the waste can pollute the local area, changing conditions so that some local species die out; diseases from the farmed fish (such as lice) can spread to wild fish and kill them, however, on the other hand, farming fish reduces fishing of wild fish.
How can we use kitchen and garden waste?
Garden and kitchen waste can be used to make compost, either in the garden or by council schemes. Conditions in the compost should be controlled to encourage the growth of decay microorganisms, which grow and digest faster in conditions that are: moist, warm and aerobic (oxygen present).
What does rooting powder do and contain?
Gardners take cuttings (small pieces) of plants to grow into new plants. They dip the stalk end of the cutting into rooting powder. This contains auxins tat cause the stalk to produce roots quickly. this helps the cuttings grow well into newly developed plants
What are Gibberellins?
Gibberellins stimulate germination of seeds which increases crop yields. They also stimulate flower and fruit production, again increasing the yield. Gibberellins stimulate stem elongation. If this is done on crops like sugar cane, it increases the yield of sugar. - Gibberellins sprayed onto flowers can stop seeds developing in fruits. They can also make the fruit growe larger. Many people prefer large seedless fruit, so they are worth more money
What factors effect transpiration?
High light intensity causes the stomata to open. This increases the rate of evaporation of water from the leaf so more water is take up to replace this. Wind blows moist air away from the stomata, keeping the diffusion gradient high. So the more air movement there is, the higher the transpiration rate. The higher the temperature, the more energy water molecules have, so they move faster which means a faster rate of transpiration
What is homeostasis?
Homeostasis maintains some conditions inside the body at a more or less constant level, in response to internal and external change. Negative feedback mechanisms respond to a change in condition to help bring the condition back to a normal level
What are hormones and how are they produced and transported in and around the body?
Hormones are 'chemical messengers' that target organs in the body. Hormones are produced by endocrine glands and released into the blood. They travel around the body in the blood until they reach their target organs. Each hormone causes its target organ(s) to respond, e.g. by releasing another chemical substance. Different hormones have different target organs and cause different responses
What is meant by the acronym, ART?
Hormones are used in Assisted Reproductive Terapy (ART) including IVF treatment and clomifene therapy
What is IVF?
IVF (in-vitro fertilisation), is fertilisation that occurs outside a woman's body. This treeatment is offered to couples who are having difficulty conceiving a child (i.e. having a problem with fertilisation). 1) Fertility drugs are given to woman to stimulate eggs to mature 2) Eggs are taken from the ovaries 3) The eggs are mixed with sperm in a dish for fertilisation 4) The fertilised eggs develop into embryos 5) When the embryos are tiny balls of cells, one or two of them are plafced in the mother's womb to develop
How have plantys adapted to dry conditions?
In the desert where it is very hot and dry, or sand dunes where it is windy and there is little fresh water because sand does not hold much water, plants such as marram grass have developed adaptations to their leaves. for example: . stomata sunk in pits to reduce water loss . waxy cuticle to reduce water loss . rolled leaf to reduce air movement around the stomata . leaf hairs to trap moist air round stomata
What effect does an increasing human population have on food security?
Increasing human populations need greater food security. This means they need a reliable and adequate food supply. As people become better off, there is a great demand for meat and fish
Why is it important to controll body temperature?
It is important to control body temperature because enzymes in the main organs are most active at this temperature. The skin plays an important role in thermoregulation: .sweat gland - releases sweat when warm to loses heat by evaporation .Vasodilation/vasoconstriction - changes blood flow through surface capillaries depending on temperature .hair muscle - contracts when cold to pull hairs upright, trapping and insulating layer of air. When warm, hairs lie flat
What is Kidney failure?
Kidney failure is when the kidney stops working properly, so excess water, mineral ions and urea build up in the body. People with kidney failure may be treated with dialysis, or by transplant of a healthy kidney.
What is vasodilation?
Less bloos flows through deep skin blood vessels and more blood flows through surface capillaries. This increases head loss by radiation - this increases flow of warm blood near skin, so heat can transfer easily to air.
What is the carbon cycle?
Living organisms need substances from the environment. As the amount of these on Earth is limited, they are recycled through both living (biotic) and non-living (abiotic) parts of the ecosystem. The carbon cycle shows how the element carbon passes through the environment and living organisms.
What are the limiting factors of photosynthesis?
Low temperature, dim light and low carbon-dioxide concentration all limit the rate of photosynthesis
How do some organisms deter predators?
Many organisms are the food of other animals. Some animals and plants have special features that deter predators: .some advertise they are very poisonous with very bright colours .some animals use bright colours to make them look more frightening e.g. the 'eye' designs on butterflies .some plants have big thorns; other plants are poisonous
What is vasoconstriction?
More blood flows through deep skin blood vessels so less blood flows through surface capillaries - this keeps warm blood deeper in the skin so less heat is transferred to the air
Where are most chloroplasts found?
Most chloroplasts are found in the palisade mesophyll cells near the upper surface of the leaf
What is meant by mutualism?
Mutualism is used to describe a relationship where two organisms live closely together in a way that benefits both. Examples include: 1) The Oxpecker bird and the herbivore: .oxpecker bird benefits by getting food .herbivore benefits from loss of skin parasites 2) Sharks and cleaner fish: .The Shark benefits from the loss of dead skin and parasites .The cleaner fish benefit from getting food 3) Nitrogen fixing bacteria and the legume plant: .nitrogen-fixing bacteria in root nodules are protected from the environment and get food from the plant .legume plant gets nitrogen compounds for healthy growth from the bacteria
What are Hormones and Nerves?
Nerves and hormones both help you to respond to changes in the environment and in your body. Hormones usually have a long-lived effect while nerves have a short-term effect. Nerve impulses work quickly whilst hormones take longer to work
What are non-indigenous species?
Non-indigenous species (organisms that are not found naturally in the area) may be introduced on purpose or accidentally to an area. These animals may harm the ecosystem as they may reproduce in excess due to the lack of natural predators in the area furthermore, they may out-compete native species for food and other resources. Yet, they may in fact boost the local ecosystem - providing food for native species.
Describe energy transfers between trophic levels
Not all the energy from one trophic level is stored as biomass in the next level. Some of it is transferred to the environment. Energy that is transferred as heating is less useful to organisms as it cannot be transferred as biomass again. Examples of energy tansfer include: Producers: 1) energy transferred to plant by light during photosynthesis 2) energy from respiration transferred to surroundings by heat 3) energy stored in new plant biomass which can be transferred to herbivores in their food Or, Rabbits (herbivores): 1) energy stored in biomass of food 2) energy stored as new animal biomass which can be transferred to carnivored in their food 3) energy stored in substances in faeces and urine 4) energy from respiration transferred to surroundings by heat
Give details of a temporary treatment of kidney failure?
One temporary treatment of kidney failure is dialysis - which must be carried out every two to three days, usually in a hospital. Dialysis tubing, which is partially permeable, is attached to a vein - usually in the forearm; the tubing then moves through a closed system of dialysis fluid which contaoins the same concentration of useful substances as blood so glucose and useful mineral ions are not lost. Therefore diffusion restores normal concentrations of dissolved substances in the blood whilst it also facilitates the diffusion of urea out of the blood and into the fluid.
Describe competition between plants and animals
Organisms need a supply of materials from their surroundings, and sometimes from other living organisms, so they can survive and reproduce. This means there is competition between organisms for materials that are in limited supply. ...between plants: .competition for light and space .competition for water and nutrients ...between animals: Animals may compete with each other for: .food .mates for reproduction .territory ( space for feeding, reproduction annd rearing young)
What is osmoregulation?
Osmoregulation controls how much water is lost in urine, and so controls the amount of water in the body. This stops animal cells from swelling up or shrinking by osmosis if the water content of the body changes. Normal water content in body: .Your body gains water from food and trink - too much water in the body - the brain detects change and causes more water to be excreted in urine - lots of watery urine - normal water content in body Or .Your body loses water when breathing out, in sweat, and in urine - too little water in the body - the brain detects change and causes less water to be excreted in urine - small amount of concentated urine
What is photosynthesis?
Photosynthesis is the process that plants and algae use to make their own food. Plants are called producers because they produce their own food. Photsynthetic organisms are the main producers of food and therefore biomass. Biomass is the mass of living material at a particular stage in a food chain
What are Auxins?
Plant hormones are chemicals that cause changes in plants. Auxins are plant hormones that make cells grow longer. Auxins are affected by light and cause phototropism in shoots. In a shoot, where light is coming from one side: .auxin is produced in cells near the top of a shoot .auxins move to shaded part of shoot .auxins then cause cell elongation and lift that side of the shoot to a vertial position.
What role does the phloem play in the transportation of sucrose around a plant?
Plants have two seperate transport systems: the xylem and phloem; dissolved sugars are transported around a plant in phloem. 1) Sucrose is produced in leaves from glucose formed during photosynthesis 2) Dissolved sucrose is carried around the plant in the phloem - dissolved sucrose is needed for growth in growing regions, e.g. bud 3) Phloem in plant veins - dissolved sucrose is carried around the plant in phloem 4) Dissolved sugars converted to starch and stored in storage organs so they can be used later - e.g. potato
How have plantys adapted to tropical conditions?
Plants that grow on the ground of a tropical rainforest have to be adapted to wet conditions with low light intensity. Adaptations include: . large leaves to take in as much light as possible . stems and leaves that climb up the trees to obtain more light, with the plant's roots still in the ground . leaves with 'drip tips' so water runs off them
What is plama?
Plasma comprises around 55% of the blood - it contains many dissolved substances, such as carbon dioxide and glucose and carries the blood cells through the blood vessels.
What are platelets?
Platelets are fragments of larger cells. They have no nucleus. Their function is to cause blood to clot when a blood vessel has been damaged. The clot blocks the wound and prevents pathogens getting into the blood - they comprise less that 1% of total blood content
What are red blood cells?
Red blood cells contain haemoglobin which carries oxygen. The biconcave shape of a red blood cell means it has a large surface area. This means it is easier for oxygen to diffuse into or out of the cell. The cell has no nucleus. This means the cell has more room for haemoglobin to carry more oxygen - they comprises approximately 45% of total blood content
What is reforestation?
Reforestation is replanting forests where they have been destroyed, for example to create farmland. Advantages include: .Restores habitat for species that are endangered. Restoring rain forest, for example, helps to conserve many species .Reduces the concentration of carbon dioxide in the air as the trees photosynthesise .Tree roots bind the soil together and reduce the effects of soil erosion .Affects local climate, for example reducing the range of temperature variation
How can we prevent decay?
Refrigerating food makes it last longer because the temperature is too cold for most microorganisms to grow quickly. Salting food makes it last longer because it causes water to move out of bacterial cells by osmosis, so there is not enough water in the microorganism's cells for them to grow. Packing food in nitrogen makes it last longer because it means there is no oxygen for microorganisms to respire
How do selective weedkillers work?
Selective weedkillers contain auxins. Weed plants compete with crop plants for water and minerals from the soil, weed plans often are broad leaved whereas, crop plants are often narrow leaved. As a result, broad-leaved plants absorb more of the auxins than narrow-leaved plants. This causes the to grow too quickly and die. This leads to the crop plants getting more water and minerals, due to loss of competition, and so grow better.
What are indicator species?
Some species are well adapted to living in polluted condition. Other species can only live where there is no pollution. The presence or absence of these indicator species can show us whether or not there is pollution. Changes in the abundance of these species can show changes in the level of pollution.
How does exchange occur in capillaries?
Substances are exchanged between the body cells and blood in capillaries. Capillaries are adapted to their function of exchanging substances between the blood and body cells - only one blood cell wide and with a wall only one cell thick
What is the Phloem?
The Phloem contains sieve tube elements which have very little cytoplasm so there is a lot of space to transport sucrose and other nutrients. It also contains companion cells which have lots of mitochondria. These supply energy from respiration for active transport of sucrose into and out of sieve tubes. sucrose is translocated around the plant in the phloem sieve tubes
What is the stomata?
The Stomata are mainly found on the lower surface of the leaf 1) When guard cells take in water by osmosis, they swell and this causes the stoma to open 2) When guard cells lose water, they become flacid and the stoma closes
What is the role of ADH?
The amount of water reabsorbed from the nephrons is controlled by a hormone called ADH (antidiuretic hormone). This regulates the water content of the blood (osmoregulation). If the brain senses there is not enough water in the blood it stimulates the pituitary gland to secrete more ADH. The increase in ADH makes the collecting ducts more permeable; so more water is reabsorbed from the kidney tubule back into the blood leading to a small volume of concentrated urine being produced. On the other hand, if the brain senses there is too much water in the blood it stimulates the pituitary gland to decrease he secretion of ADH which, in turn, makes the collecting ducts less permeable leading to a large volume of dilute urine being produced as less water is reabsorbed from the tubule back into the blood. ADH increases the permeability of the cell membranes in the collecting duct of the nephron so that more water is absorbed from the urine by osmosis
What is a belt transect?
The effect of abiotic and biotic factors on where organisms live (their distribution) can be studied using quadrats placed along a belt transect - choosing the number of quadrat samples to take is usually a trad off - a trade-off between taking more samples (more accurate) and taking fewer samples (quicker). Changes in factors (such as temperature, light intensity, trampling) are also recorded at each quadrat position. This makes it easier to link a change in distribution with a change in physical factor.
What are the factors affecting the rate of diffusion?
The effectiveness of an exchange surface increases with: . increase in surface area - e.g. alveoli in lungs . a shorter distance for diffusion - e.g. surfaces are one cell thick . maintenance of a high concentration gradient - e.g. animals have an efficient blood supply lungs are ventilated
What is the function of the heart?
The heart pumps blood around the body. The heart and the blody. The heart and the blood vessels together make up the circulatory system, which delivers oxygen and nutrients such as glucose to all parts of the body.
Give an example of how an organ is adapted to make exchange efficient?
The lungs have adapted to exchange gases, and the small intestine has adapted to exchange solutes
What are the controls of decay rate?
The rate of decomposition is affected by: .warm temperatures because this increases enzyme activity in microorganisms .water content because microorganisms need water for many cell processes to work .oxygen availabilty because microorganisms need oxygen for respiration
What is the function of the urinary system?
The urinary system maintains water balance, removes excess substances absorbed from food and removes waste products from metabolism such as urea from the breakdown of proteins
Describe the structure of a vein
The vein has a tinner wall than an artery allowing for a large space to accomodate ease of blood flow back to the heart. Veins have valves to stop blood flowing backwards, so that it is returned to the heart
What is the structure of the heart?
The vena cava brings deoxygenated blood from the body to the heart and into the right atrium befire it flows through to the right ventricle - valves prevent blood flowing backwards through the heart (backflow) and the pulmonary artert carries deoxygenated blood from heart to the lungs. The pulmonary vein brings oxgygenated blood from lungs to the heart and into the left ventricle, through the left atrium before the aorta carries deoxygenated blood from heart to body. . the left ventricle muscle wall is thicker than the right ventricle as it pushes blood all round the body
What is thermoregulation?
Thermoregulation keeps core body temperature steady at about 37 degrees C. This is controlled by the hypothalamus, which triggers changes in the skin and muscles. The thermoregulatory centre in th hypothalamus of the brain monitors and controls core body temperature. 1) Body temperature rises due to hot environment or exercise - hypothalaus in brain detects rise and causes body responses - changes triggered in blood flow so more flows near the skin surface; sweat glands release more sweat onto skin surface to evaporate; sebaceous glands produce oil that helps sweat spread out over skin - increases transfer of energy to surroundings OR 2) Body temperature falls due to cold environment - hypothalamus detects fall and causes body responses - changes triggered in blood flow so less blood flows near skin surface; sweat glands stop producing sweat - body hairs raised by erector muscles in skin (causing 'goosebumps') - reduces transfer of energy to surroundings - reduces transfer of energy to surroundings
What is Thyroxine?
Thyroxine is a hormone that controls metabolic rate. This is the rate at which the cells respire;. It is measured as the rate of energy transfers in the body.
What is translocation?
Translocation is the transport of sucrose around a plant
What is transpiration?
Transpiration is the loss of water by evaporation from the leaves. The movement of water from the roots to the leaves is called the transpiration stream.
How have plants adapted to waterlogged conditions?
Waterlogged soils have no air spaces so the root cells have difficulty obtaining enough oxygen for respiration. Adaptations include: .spongy tissue in their roots that stores oxygen .fine surface roots that take in oxygen at the water surface
What is negative feetback?
When a factor rises above a normal level a corrective mechanism is applied to lower the level of the factor and achieve a normal level, the opposite is true if a factor falls below normal.
How should sampling with quadrats be carried out?
When studying organiskms in the field, most areas are too large to cont every individual organism so we take samples and use them to draw a conclusion about the whole area. Samples are often taken with square frames called quadrats .Quadrats are placed randomly in the area .The number of study organisms is counted in each quadrat .The number of organisms in the whole area is estimated using the equation: number in whole area = mean number of organisms in one quadrat x total area/ area of one quadrat
What are the effects of excercise on the heart?
When you exercise, your heart rate increases. The harder you exercise, the more your heart rate increases. Heart rate can be measured by taking your pulse at the wrist. It is usually measures as number of beats per minute. During exercise, muscle cells are respiring faster. This means that they need more oxygen and glucose, and release more carbon dioxide. A faster heart rate means that blood is pumped faster around the body. The blood takes oxygen and glucose to cells faster and removes carbon dioxide faster
What are white blood cells?
White blood cells are larger than red blood cells, and they have a nucleus. All types of white blood cells are part of the immune system, which attacks pathogens in the body - they comprise less that 1% of total blood content
What is the Xylem?
Xylem vessels are dead cells which have no cytoplasm or cell contents. This means there is more space for water containing mineral ions to move through. They have many holes called pits in their walls to allow water and mineral ions to move out. The walls are strengthened with lignin rings, which makes them very strong and prevents them from collapsing . They have no end walls so they can form a long tube that water can flow through easily.
How can you calculate the volume of water taken up in a potometer?
You can find the volume of water taken up by finding the volume of the capillary tube between the bubble's start and finish points using the formula pie x radius squared x distance where r = radius of tube and d = distance moved by the bubble.
How could you investigate how light intensity affects the rate of photosynthesis?
You can investigate the effect of light intensity on the rate of photosynthesis by measuring the change in pH of solution around algal balls. The pH changes because carbon dioxide an acidic solution, and photosynthesis changes the concentration of carbon dioxide in the solution Appartus: .screw-top bottles (one for each distance) .algal balls (20 per bottle) .universal indicator solution .measuring cylinder .foil or black pepper .bright lamp .small tank of water (if lamp is hot) .metre ruler .universal colour chart for indicator - change in the colour solution can also be measured as change in absorbance using a colorimeter Method: 1) Place 20 algal balls and the same volume of indicator solution in each tube, and replace the screw tops 2) Check the colour of the indicator against the colour chart and record the starting pH 3) If using a hot lamp, place the water tank next to the lamp - using a water tank if the lamp is hot helps control for temperature, which will also vary with distance from the lamp - Safety: Take care if using a lamp with a hot lamp 4) Use the metre rules to place the tubes at specific distances from the lamp, on the opposite side of the tank 5) Leave the tubes for 1 - 2 hours 6) Record distance and pH of each tube, using the colour chart for identifying the pH 7) Calculate the rate of change in pH per hour in each tube Results: Draw a graph of your results to show distance against rate of change in pH Conclusion: As distance increases, light intensity falls and so the rate of photosynthesis decreases. This is because energy transferred by light is needed for photosynthesis to take place. - instead of distance, light intensity could be measured directly using a light meter.
What effect does light have on the rate of photosynthesis?
You can measure the effect of light intensity on the rate of photosynthesis by measuring the rate at which oxygen is given off by a piece of pondweed. You can use the apparatus shown to investigate the effect of light intensity using bright and dim light
How would you use a potometer?
You can measure the rate of transpiration using a potometer. 1) Note the position of the air bubble on the ruler at the start of the investigation 2) Note the position of the bubble on the ruler after a known number of minutes 3) Divide the distance moved by the bubble by the time taken. Rate of transpiration can be measured as distance moved/ time taken
Why must you consider safety and living organisms when investigating respiration?
You must consider the safe and ethical use of working with living organisms . You should minimuse harm to small invertebrates, and return them to their natural environment as soon as possible. You should also wash your hands thoroughly after working with living organisms
What are the factors affecting respiration?
You should remeber that respiration is affected by environmental factors, particularly temperature, and that microorganisms also respire. So the investigation will need controls. Control for temperature - e.g. by keeping respirometers in a water bath during the experiment. Control for something other than the study organisms affecting the gas volume - e.g. by using the same volume of an inert substance, such as gas beads instead of seeds
What is the photosynthesis equation?
carbon dioxide + water --> glucose + oxygen
What is the formula for cardiac output?
cardia output = stroke volume x heart rate
