Chapter 6 IB Biology

Distinguish between type I and type II diabetes.

Type 1 Diabetes usually occurs during early childhood and its when the body does not produce sufficient insulin and is caused by destrucution of beta cells and requires insulin injections to regulate the glucose levels. Whereas Type 2 Diabetes occurs in adulthood and is when the body does not respond to insulin and is caused by down regulation of insulin receptors. it can be controlled with a carefully monitored diet.

What causes air to be breathed out by the lungs? A. The diaphragm relaxes and the ribs fall. B. The ribs rise and the external intercostal muscles relax. C. The internal intercostal muscles contract and the ribs rise. D. The diaphragm contracts and internal intercostal muscles contract.

a

What is a role of the hypothalamus in homeostasis? A. Monitoring body temperature B. Monitoring blood glucose concentration C. Secretion of glucagon D. Secretion of sweat

a

What is the main function of the large intestine? A. Absorption of water B. Digestion of fats and proteins C. Absorption of nutrients D. Recycling of digestive enzymes

a

Which structure releases glucagon? A. α cells of the pancreas B. β cells of the pancreas C. Liver cells D. Hypothalamu

a

Outline mechanisms used by the ileum to absorb amino acids.

active transport: against concentration gradient and requires ATP and protein pumps/transport proteins; facilitated diffusion: along concentration gradient, is passive/no ATP required and requires carrier/transport proteins; simple diffusion: passive/no ATP required and along concentration gradient and through protein channels; endocytosis: invagination of the cell membrane making a vesicle;

Outline how coronary thrombosis can be caused

atheroma/fatty deposits in arteries; hardening of arteries/atherosclerosis/arteriosclerosis; rough surface causes rupture of platelets; clots form in coronary artery;

Celiac disease causes the destruction of the villi cells. Which of the following is most likely to happen to people with celiac disease? A. Incomplete digestion of fats B. Poor absorption of calcium C. Increased levels of glucose in blood D. Damage in the esophagus caused by increase in acid content of the stomach

b

How do vaccines give immunity to infectious diseases? A. They kill pathogenic microbes. B. They produce an immune response. C. They contain antibodies against pathogens. D. They inhibit the antigen-antibody reaction.

b

Which term describes a molecule capable of triggering an immune response? A. Antibody B. Antigen C. Pathogen D. Antibiotic

b

State one cause of type II diabetes.

body becomes resistant/not responsive to insulin; pancreas does not produce enough insulin; dietary factors / genetic predisposition; lack of exercise;

A process occurs in which the inside of a neuron develops a net positive charge compared with the outside. What is the name of this process? A. Resting potential B. Repolarization C. Depolarization D. Hyperpolarization

c

What are two effects of HIV on the immune system? A. Reduction in antibody production and increase in active lymphocytes B. Increase in antibody production and decrease in red blood cells C. Reduction in antibody production and decrease in active lymphocytes D. Increase in antibody production and increase in red blood cells

c

What change occurs to the pressure and volume of the lungs when the external intercostal muscles contract? A. Both pressure and volume increase. B. Pressure increases and volume decreases. C. Pressure decreases and volume increases. D. Both pressure and volume decrease.

c

What is the function of the tRNA activating enzyme? A. It links tRNA to ribosomes. B. It links tRNA to mRNA. C. It links tRNA to a specific amino acid. D. It links an amino acid on one tRNA to an amino acid on another tRNA.

c

What prevents antibiotics from being effective against viruses? A. Viruses have a high rate of mutation. B. Viruses have no RNA. C. Viruses have no metabolism. D. Viruses have a protein shell that protects them

c

What will be happening in a person after eight hours of sleep? A. β cells in the pancreas will be producing insulin. B. Glucose will be converted into glucagon. C. α cells in the pancreas will be producing glucagon. D. Glycogen is being produced and stored in the liver and muscle cells.

c

Where in a cell are antigens found? A. In the nucleus B. In the cytoplasm C. In the plasma membrane D. On the surface of the Golgi apparatus

c

What does the digestion of starch by amylase produce? A. Lactose B. Sucrose C. Galactose D. Maltose

d

What feature of alveoli adapts them to efficient gas exchange? A. They have muscles which pump air in and out regularly. B. Their membranes are more permeable to gases than water. C. A constant blood supply flows through them. D. A dense network of capillaries surrounds them

d

Which feature maintains a high concentration gradient of gases in the ventilation system? A. Thin-walled alveoli B. Thin-walled capillaries C. A moist lining of the alveoli D. Blood flowing in the capillaries

d

State one symptom of type II diabetes

decreasing responsiveness to insulin; high blood glucose; glucose in urine; loss of weight / tiredness; increased production of urine; dehydration and thirst;

Outline factors that can lead to an individual becoming obese.

diet rich in carbohydrate/fat; too much food intake / unbalanced diet / food cheap and readily available; sedentary lifestyle / lack of training/exercise; genetic disposition/disorder; malfunction of hunger centre;

Outline two factors that affect the incidence of coronary heart disease

genetic predisposition; effect: some synthesise more cholesterol/LDL than others; e.g. factor: being male; effect: women before menopause appear to be protected by higher blood estrogen levels which men do not have; e.g.: factor: obesity; effect: excess weight raises blood pressure/blood cholesterol/ triglyceride levels / lowers HDL/good cholesterol levels;

Outline factors that affect the incidence of coronary heart disease.

genetic — some people predisposed for high cholesterol levels / high blood pressure; age —older people greater risk / less elasticity in arteries; sex —males at greater risk of heart disease than (pre-menopausal) women as estrogen protects against heart disease; smoking —constricts blood vessels / increases blood pressure/ heart-rate / decreases oxygenation of heart muscle; diet — increased fat/cholesterol/LDL in blood leads to plaque formation in arteries; exercise — helps reduce high blood pressure / exercise reduces the rate of fatty deposits building up in the inner lining of arteries/thickens the heart muscle walls so they pump blood more efficiently; obesity — increase in blood pressure / leads to plaque formation in arteries;

List two symptoms in a patient with type II diabetes.

high glucose content in blood/hyperglycemia; thirst/frequent urination; slow-healing sores; tiredness; red/swollen gums; blurred vision/blindness; kidney/back pain; nerve damage; glucose in urine; erectile dysfunction

Example of a hormone:

insulin

State an example of a protein hormone.

insulin / glucagon / prolactin / somatotrophin

Describe how phagocytic leucocytes may act as a defence against disease.

phagocytic leucocyte occurs in blood and body tissue fluids; phagocytic leucocyte detects pathogen/foreign material; leucocyte surrounds/engulfs pathogen / endocytosis / phagocytosis; membrane forms around pathogen to form a vacuole; lysosomes digest contents of vacuoles

Discuss the ethical issues surrounding IVF

pros/positive considerations: 3 max chance for infertile couples to have children; decision to have children is clearly a conscious one due to difficulty of becoming pregnant; genetic screening of embryos could decrease suffering from genetic diseases; spare embryos can safely be stored for future pregnancies/used for stem cell research; cons/negative considerations: 3 max IVF is expensive and might not be equally accessible; success rate is low therefore it is stressful for the couple; it is not natural/cultural/religious objections; could lead to eugenics/gender choice; could lead to (unwanted) multiple pregnancies with associated risks; production and storage of unused embryos / associated legal issues / extra embryos may be used for (stem cell) research; inherited forms of infertility might be passed on to children;

Outline two roles of the liver

storage of nutrients; detoxification of poisons; breakdown of hemoglobin; production of bile pigments; synthesis of plasma proteins; synthesis of cholesterol;

Explain how the structure of an artery allows it to carry out its function efficiently

) thick wall to withstand high blood pressures/avoid bursting/leaks; many muscle fibres to help pump blood; many elastic fibres to stretch and pump blood after each heart beat; narrow lumen to maintain high pressure/because blood flows along rapidly; thick outer layer of collagen to give strength/prevent aneurism; no valves as pressure is high enough to prevent backflow; endothelium/smooth inner lining to reduce friction;

How is in vitro fertilization different from natural fertilization in humans? A. In vitro fertilization involves artificial injection of sperm into the uterus B. In vitro fertilization only involves one parent C. In vitro fertilization happens outside the body D. In vitro fertilization uses stem cells instead of eggs

C

Outline the roles of FSH in the menstrual cycle

FSH stimulates follicle development; FSH stimulates estrogen secretion (by the follicle/ovary);

Outline the levels of each of the hormones that control the menstrual cycle immediately before ovulation

LH levels very high / LH surge FSH levels are high estrogen levels are high progesterone levels are very low

List three roles of testosterone in males

Pre-natal development of male genitalia Development of secondary sex characteristics Maintenance of sex drive (libido)

Explain the role of the SA (sinoatrial) node in the cardiac cycle.

SA node is located in the wall of right atrium of heart muscle; has characteristics of both nerve and muscle tissue; SA node initiates each impulse; acts as pacemaker of the heart; no nerve impulses needed for contraction / myogenic; connected to nerves which slow/accelerate heart rate; impulses spread out in all directions through walls of atria; stimulates atrial systole/contraction; fibres in walls of atria prevent impulses from reaching ventricles; impulses reach AV node (after atrial contraction);

Distinguish between the energy content per 100 g of fat, protein and carbohydrate.

(per 100 g) fat contains more energy than protein or carbohydrate / fat has higher energy content (per 100 g); fat contains (approximately) twice the number of joules/energy per gram than proteins and/or carbohydrates; (per 100 g) fats have approximately 4000 kJ, whereas carbohydrates have 1760 kJ and proteins have 1720 kJ;

What occurs during the blood clotting process? A. Prothrombin is converted into thrombin which acts on fibrinogen. B. Prothrombin is converted into thrombin which acts on fibrin. C. Fibrinogen is converted into fibrin which acts on prothrombin. D. Fibrinogen is converted into fibrin which acts on thrombin

A

Which of the following statements about antibodies is correct? A. Antibodies are polypeptides. B. Antibodies are produced by the bone marrow. C. Antibodies are pathogenic foreign substances. D. Antibodies kill bacteria but not viruses.

A

Describe the need for a ventilation system in humans

A ventilation system is needed to maintain the concentration gradients of gases in the alveoli. Diffusion of gases occurs due to the concentration gradient of oxygen and carbon dioxide between the alveoli and the blood. The body needs to get rid of carbon dioxide which is a product of cell respiration and needs to take in oxygen as it is needed for cell respiration to make ATP. There must be a low concentration of carbon dioxide in the alveoli so that carbon dioxide can diffuse out of the blood in the capillaries and into the alveoli. Also there must be a high concentration of oxygen in the in the alveoli so that oxygen can diffuse into the blood in the capillaries from the alveoli. The ventilation system makes this possible by getting rid of the carbon dioxide in the alveoli and bringing in more oxygen.

State the hormone that affects heart rate.

Adrenalin

Describe the relationship between the structure and function of blood vessels

Arteries have a thick outer layer of longitudinal collagen and elastic fibers to avoid leaks and bulges. They have a thick wall which is essential to withstand the high pressures. They also have thick layers of circular elastic fibres and muscle fibres to help pump the blood through after each contraction of the heart. In addition the narrow lumen maintains the high pressure inside the arteries. Veins are made up of thin layers with a few circular elastic fibres and muscle fibres. This is because blood does not flow in pulses and so the vein walls cannot help pump the blood on. Veins also have thin walls which allows the near by muscles to press against them so that they become flat. This helps the blood to be pushed forwards towards the heart. There is only a thin outer layer of longitudinal collagen and elastic fibres as there is low pressure inside the vein and so little chance of bursting. Finally, a wide lumen is needed to accommodate the slow flowing blood due to the low pressure. Capillaries are made up of a wall that is only one cell layer thick and results in the distance for diffusion in and out of the capillary being very small so that diffusion can occur rapidly. They also contain pores within the their wall which allow some plasma to leak out and form tissue fluid. Phagocytes can also pass through these pores to help fight infections. In addition, the lumen of the capillaries is very narrow. This means that many capillaries can fit in a small space, increasing the surface area for diffusion.

What causes a resting potential to develop in a neuron? A. Diffusion of sodium and potassium ions B. Active transport of sodium and potassium ions C. Active transport of sodium and diffusion of chloride ions D. Active transport of potassium and diffusion of chloride ions

B

What normally prevents the membranes of the alveoli from sticking together during expiration? A. The thickness of the single-cell layer of alveoli membranes B. The secretion of fluids in the inner surface of the alveoli C. The pressure within the thoracic cavity D. The dense net of capillaries covering the alveoli

B

Which muscles contract to cause air to pass out from the lungs through the bronchioles? A. Internal intercostal muscles and diaphragm B. Internal intercostal muscles and abdomen wall muscles C. External intercostal muscles and diaphragm D. External intercostal muscles and abdomen wall muscles

B

William Harvey discovered that blood flows away from the heart in arteries and back to the heart in veins. What hypothesis could be developed from this discovery? A. The human body contains both arteries and veins. B. Blood vessels link up arteries to veins. C. How blood moves from arteries into veins. D. Veins are connected to the left side of the heart and arteries to the right side.

B

A number of different proteins are involved in nerve function. Which of the following does not require a membrane protein? A. Active transport of sodium B. Diffusion of K+ into the cell C. Diffusion of the neurotransmitter across the synapse D. Binding of the neurotransmitter to the post-synaptic membrane

C

What is a role of the pacemaker or sinoatrial node (SAN)? A. To initiate contraction of the ventricle B. To pass the excitation through Purkinje fibres C. To originate excitation in myogenic muscle D. To cause the relaxation of the atria

C

Which factors related to mucous membranes protect the body against microbes? I. Production of lysozyme II. Secretion of alkaline solutions III. Trapping of microbes A. I and II only B. II and III only C. I and III only D. I, II and III

C

Which muscles contract to cause air to pass into the lungs through the trachea? A. Internal intercostal muscles and diaphragm B. Internal intercostal muscles and abdomen wall muscles C. External intercostal muscles and diaphragm D. External intercostal muscles and abdomen wall muscles

C

Which vessel directly supplies the heart muscle with blood? A. The aorta B. The pulmonary artery C. The coronary artery D. The pulmonary vein

C

Outline the cause and transmission of AIDS

Cause: HIV causes AIDS (acquired immunodeficiency syndrome). A syndrome is a group of symptoms that are found together. HIV destroys a type of lymphocyte which is vital for antibody production. Over the years, less active lymphocytes are produced which leads to a fall in the amount of antibodies. Pathogens that would normally be easily controlled by the body in healthy individuals can cause serious consequences and eventually lead to death for patients affected by HIV. The immune system is considerably weakened. Transmission: HIV is transmitted through body fluids from an infected person to an uninfected one. This can occur through vaginal and anal intercourse as well as oral sex if there are cuts or tears in the vagina, penis, mouth or intestine. It can also be transmitted by hypodermic needles that are shared by intravenous drug abusers. The small amount of blood present on these needles after their use may contain the virus and is enough to infect another person. Another way of transmission is through the placenta from mother to child, or through cuts during childbirth or in milk during breast feeding. Finally there is a risk of transmission in transfused blood or with blood products such as Factor VIII used to treat hemophiliacs. Social implications: Relatives and friends suffer grief. Families can also suffer from a loss of income as the person infected by HIV can lose their wage if they are unable to work and are refused life insurance. Also, HIV patients may find it hard to find partners, employment and even housing. Finally, AIDS can cause fear in a population and reduce sexual activity.

Between which structures do sensory neurons carry nerve impulses? A. From receptors to muscles B. From effectors to the central nervous system (CNS) C. From the central nervous system (CNS) to receptors D. From receptors to the central nervous system (CNS)

D

The levels of hormones vary during the menstrual cycle in women. Each hormone reaches its maximum level at a different time in the cycle. In what sequence do the hormones reach their maximum level, if the cycle begins at the start of menstruation? A. LH, progesterone, FSH, estrogen B. FSH, progesterone, LH, estrogen C. LH, estrogen, FSH, progesterone D. FSH, estrogen, LH, progesterone

D

Which of the following is part of the process of cellular respiration? A. Changes in the volume of the thoracic cavity B. Exchange of gases across the surface of the alveoli C. Exchange of gases across the surface of capillaries D. Glycolysis

D

Explain the need for enzymes in digestion.

Enzymes are biological catalysts which speed up the rate of a chemical reaction (e.g. digestion) by lowering the activation energy Enzymes allow digestive processes to occur at body temperature and at sufficient speed to meet the organism's survival requirements Enzymes are specific for a given substrate and so can allow digestion of certain molecules to occur independently of others for absorption/diffusion into blood

Outline the need for enzymes in the digestive system.

Enzymes are biological catalysts which speed up the rate of a chemical reaction (i.e. digestion) by lowering activation energy Enzymes allow digestive processes to therefore occur at body temperatures and at sufficient speeds for survival requirements Enzymes are specific for a substrate and so can allow digestion of certain molecules to occur independently in distinct locations

Outline the roles of LH and FSH in the menstrual cycle, including the timing of their secretion during the cycle

FSH is secreted at the start of the cycle / early in the cycle / days 1 to 5 / when progesterone / estrogen is low FSH stimulates follicle development FSH stimulates secretion of estrogen (by the follicle / ovary) LH is secreted in the middle of the cycle / before ovulation / days 10 to 14 LH stimulates ovulation LH stimulates the development of the corpus luteum LH stimulates less estrogen more progesterone secretion / high progesterone / estrogen inhibits FSH and LH release

Outline the role of hormones in the menstrual cycle in human females

FSH is secreted by the pituitary gland and its levels start to rise. This stimulates the follicle to develop and the follicle cells to secret estrogen. Estrogen then causes the follicle cells to make more FSH receptors so that these can respond more strongly to the FSH. This is positive feedback and causes the estrogen levels to increase and stimulate the thickening of the endometrium (uterus lining). Estrogen levels increase to a peak and by doing so it stimulates LH secretion from the pituitary gland. LH then increases to its peak and causes ovulation (release of egg from the follicle). LH then stimulates the follicle cells to secrete less estrogen and more progesterone. Once ovulation has occurred, LH stimulated the follicle to develop into the corpus luteum. The corpus luteum then starts to secrete high amounts of progesterone. This prepares the uterine lining for an embryo. The high levels of estrogen and progesterone then start to inhibit FSH and LH. If no embryo develops the levels of estrogen and progesterone fall. This stimulates menstruation (break down of the uterine lining). When the levels of these two hormones are low enough FSH and LH start to be secreted again. FSH levels rise once again and a new menstrual cycle begins.

Outline the process of in vitro fertilization (IVF).

For a period of three weeks, the women has to have a drug injected to stop her normal menstrual cycle. After these three weeks, high doses of FSH are injected once a day for 10-12 days so that many follicles develop in the ovaries of the women. HCG (another hormone) is injected 36 hours before the collection of the eggs. HCG loosens the eggs in the follicles and makes them mature. The man needs to ejaculate into a jar so that sperm can be collected from the semen. The sperm are processed to concentrate the healthiest ones. A device that is inserted through the wall of the vagina is used to extract the eggs from the follicles. Each egg is then mixed with sperm in a shallow dish. The dishes are then put into an incubator overnight. The next day the dishes are looked at to see if fertilization has happened. If fertilization has been successful, two or three of the embryos are chosen to be placed in the uterus by the use of a long plastic tube. A pregnancy test is done a few weeks later to find out if any of the embryos have implanted. A scan is done a few weeks later to find out if the pregnancy is progressing normally.

Explain the principle of homeostasis with reference to the control of body temperature.

Homeostasis is the tendency of an organism or cell to maintain a constant internal environment within tolerance limits. The hypothalamus is responsible for monitoring the temperature of the blood which is normally close to 37 degrees. If there are significant fluctuations from this set point, the hypothalamus sends signals (messages carried by neurons) to different parts of the body to restore the temperature back to the set point. This is done through negative feedback. When body temperature rises, the following cooling mechanisms may occur: Vasodilation: The skin arterioles dilate, bringing blood into closer proximity to the body surface and allowing for heat transfer (convective cooling) Sweating: Sweat glands release sweat, which which is evaporated at the cost of latent heat in the air, thus cooling the body (evaporative cooling) When body temperature falls, the following heating mechanisms may occur: Vasoconstriction: The skin arterioles constrict, moving blood away from the surface of the body, thus retaining the heat carried within the blood Shivering: Muscles begin to shake in small movements, expending energy through cell respiration (which produces heat as a by-product) Other mechanisms through which homeotherms may regulate their body temperature include: Piloerection: Animals with furry coats can make their hair stand on end (piloerection), trapping pockets of warm air close to the body surface Behavioural responses: Animals may physically respond to environmental conditions in a bid to regulate temperature (e.g. bathing, burrowing, etc.)

Explain how the structure of the villus is adapted for absorption.

Intestinal villi contain several key features which facilitate the absorption of digestive products (monomers, ions and vitamins): Microvilli - Ruffling of epithelial membrane further increases surface area Rich blood supply - Dense capillary network rapidly transports absorbed products Single layer epithelium - Minimises diffusion distance between lumen and blood Lacteals - Absorbs lipids from the intestine into the lymphatic system Intestinal glands - Exocrine pits (crypts of Lieberkuhn) release digestive juices Membrane proteins - Facilitates transport of digested materials into epithelial cells

Describe how pancreatic cells directly affect blood glucose levels.

Response to blood glucose levels above the set point: β cells in the pancreatic islets produce insulin. Insulin stimulates muscle cells and the liver cells to take up glucose from the blood and convert it into glycogen. These are then stored in the form of granules in the cytoplasm of cells. Also, other types of cells are stimulated to take up glucose and use it for cell respiration instead of fat. All of these processes lower the levels of glucose in the blood. Response to blood glucose levels below the set point α cells in the pancreatic islets produce glucagon. Glucagon stimulates the liver cells to convert glycogen back into glucose and release this glucose into the blood. This raises the glucose levels in the blood.

Outline the control of the heartbeat

The heart muscle can contract by itself, without the stimulation of a nerve. This is called myogenic muscle contraction. The region that initiates each contraction is found in the wall of the right atrium and is called the pacemaker. Every time the pacemaker sends out a signal, a heartbeat results. The pacemaker is under the influence of nerves and adrenaline. One nerve carries messages from the medulla of the brain to the pacemaker and speeds up the beating of the heart. Another nerve carries messages from the medulla of the brain to the pacemaker and slows down the beating of the heart. Finally, adrenaline (epinephrine) is carried by the blood and once it reaches the pacemaker it signals it to increase the beating of the heart

Explain the mechanisms involved in the ventilation of the lungs

The mechanism of ventilation: Air is exhaled into lungs via trachea - bronchi - bronchioles. Exhaled via same route. Muscles lower and raise the pressure inside the lungs to cause movement of air. Inhaling: (1) External intercostal muscles contracts - moving ribcage up and out. (2) Diaphragm contracts - becomes flatter and moves down. (3) Volume of the thorax is increased by these muscle movements. (4) Pressure inside the thorax drops below atmospheric pressure. (5) Air flows into the lungs until the pressure inside the lungs rises to atmospheric pressure. Exhaling: (1) Internal intercostal muscles contract - the ribcage moves down and in. (2) Abdominal muscle contract - pushes the diaphragm up into a dome shape. (3) Volume of the thorax decreases by these muscles movements. (4) Pressure inside the thorax rises above atmospheric pressure. (5) Air flows out of the lungs until the pressure inside the lungs falls to atmospheric pressure.

Describe the processes involved in blood clotting.

The process by which blood clots are formed involves a complex set of reactions collectively called the coagulation cascade This cascade is stimulated by clotting factors released from damaged cells (extrinsic pathway) and platelets (intrinsic pathway) The coagulation cascade involves many intermediary steps, however the principal events are as follows: Clotting factors cause platelets to become sticky and adhere to the damaged region to form a solid plug These factors also initiate localised vasoconstriction to reduce blood flow through the damaged region Additionally, clotting factors trigger the conversion of the inactive zymogen prothrombin into the activated enzyme thrombin Thrombin in turn catalyses the conversion of the soluble plasma protein fibrinogen into an insolube fibrous form called fibrin The fibrin strands form a mesh of fibres around the platelet plug and traps blood cells to form a temporary clot When the damaged region is completely repaired, an enzyme (plasmin) is activated to dissolve the clot

Explain how the structure of a villus in the small intestine is related to its function.

The structure of the villus is very specific. Firstly there is a great number of them so this increases the surface area for absorption in the small intestine. In addition the villi also have their own projections which are called microvilli. The many microvilli increase the surface area for absorption further. These microvilli have protein channels and pumps in their membranes to allow the rapid absorption of food by facilitated diffusion and active transport. Also, the villi contains an epithelial layer which is only one cell layer thick so that food can pass through easily and be absorbed quickly. The blood capillaries in the villus are very closely associated with the epithelium so that the distance for the diffusion of the food molecules is small. This thin layer of cells contains mitochondria to provide the ATP needed for the active transport of certain food molecules. Finally, there is a lacteal branch at the centre of the villus which carries away fats after absorption.

Define tidal volume.

The volume of air inhaled and exhaled per breath

Which muscle action is associated with an increase in the volume of the thoracic cavity during inspiration? A. The diaphragm contracts. B. The external intercostal muscles relax. C. The internal intercostal muscles contract. D. The abdominal muscles contract.

a

Which of the following describes arteries? A. They have thick muscular walls. B. They usually contain valves. C. They carry blood towards the heart. D. They carry blood from the lungs.

a

Describe how the structure of the alveoli increases surface area for gas exchange.

alveolus is very small but the lung has many so there is a large surface area for gas exchange. The wall has a single layer of thin cells so diffusion is quick. The alveolus are covered in capillary networks allowing oxygen to diffuse in and carbon to diffuse out.

The pumping of blood is a vital process. Explain the roles of the atria and ventricles in the pumping of blood.

atria collect blood from veins (vena cava/pulmonary); collect blood while ventricles are contracting; atria pump blood into ventricles/ensure ventricles are full; ventricles pump blood into arteries/out of the heart; ventricles pump blood at high pressure because of their thicker, muscular walls; mention of heart valves working with atria and ventricles to keep blood moving; left ventricle pumps blood to systems and right ventricle pumps blood to lungs;

A blood clot forms around a fibrous network of protein. What is the protein? A. Fibrinogen B. Fibrin C. Thrombin D. Thrombokinase

b

Which vessel carries deoxygenated blood? A. The coronary artery B. The pulmonary artery C. The aorta D. The pulmonary vein

b

What is placed into the uterus after the process of in vitro fertilization (IVF)? A. Eggs B. Sperm C. Embryos D. Fetuses

c

What is the correct sequence of factors involved in blood clotting? A. platelets → clotting factors → fibrin → fibrinogen B. clotting factors → platelets → fibrinogen → fibrin C. platelets → clotting factors → fibrinogen → fibrin D. clotting factors → platelets → fibrin → fibrinogen

c

Which chamber of the heart has the thickest walls? A. Left atrium B. Right atrium C. Left ventricle D. Right ventricle

c

Which event directly leads to an action potential? A. Fusion of vesicles with the pre-synaptic membrane B. Diffusion of neurotransmitter across the synaptic cleft C. Membrane potential reaches the threshold potential D. Breakdown of the neurotransmitter

c

Which of the following is transported by the blood? A. Gametes B. Glycogen C. Heat D. Starch

c

Why are antibiotics effective against bacteria but not viruses? A. Viruses can hide inside host cells. B. Bacteria are recognized as pathogens but viruses are not. C. The enzymes of bacteria can be inhibited by antibiotics. D. Viruses are resistant to antibiotics.

c

List two materials that are not absorbed but are egested by the body.

cellulose / lignin / bile pigments / bacteria / intestinal cells

State two materials which are not absorbed in the ileum.

cellulose/fibres lignin bile pigment bacteria intestinal cells

Define hormones

chemical substances, released from endocrine glands, that travel through the bloodstream to targeted tissues

What does the nucleus of a human lymphocyte contain? A. Only the genes to produce a specific antigen B. Only the genes to produce a range of antibodies C. Only the genes that control the growth and development of a lymphocyte D. The whole genetic information for a human

d

Explain how and why ventilation rate varies with exercise.

during exercise the rate of tissue respiration increases/more carbon dioxide produced; carbon dioxide production in the tissues exceeds the rate of breathing it out; increase in carbonic acid / increase in H+ ions / pH drops in the blood plasma; lactic acid (in strenuous exercise) reduces pH; chemoreceptors/chemosensors detect change in pH/increase in carbon dioxide/ decrease in oxygen; receptors in the carotid/aortic bodies; nerve impulses sent to the breathing centres of the brain; nerve impulses then sent to diaphragm/intercostal muscles; negative feedback control

Explain, using an example, how females but not males can be carriers of some recessive alleles.

females are carriers when they have dominant and recessive alleles together; recessive allele in carrier does not affect phenotype as dominant allele also present; gene is located on the X chromosome / gene is not located on Y chromosome; females are XX so can have dominant and recessive alleles/two alleles of gene; males are XY so only have dominant or recessive allele/one allele of gene; hemophilia/red-green colour blindness/other example of a sex-linked characteristic;

Outline the roles of progesterone and estrogen in the human menstrual cycle.

follicles secrete estrogen / FSH stimulates secretion of estrogen; (rapid) increase in estrogen stimulates FSH/LH production; estrogen also stimulates repair/thickening of endometrium/uterus lining; LH causes follicle to produce less estrogen/more progesterone; corpus luteum secretes more estrogen/progesterone; progesterone maintains/stimulates thickening of endometrium/uterus lining; estrogen/progesterone inhibit FSH/LH secretion; estrogen/progesterone levels fall after day 21-24 if no embryo/fertilization; lower concentration of estrogen/progesterone allows disintegration of endometrium/uterus lining / menstruation oc

Outline the need for enzymatic hydrolysis in the digestive process

large molecules cannot be absorbed; mechanical digestion only to break down food physically; enzymes breakdown large molecules into smaller ones (that can be absorbed); need several enzymes as they are substrate specific; enzymes speed up the rate of digestion considerably; higher speeds at low / normal body temperature; named example of enzyme; example of named enzyme's action;

Explain the dietary advice that should be given to a patient who has developed type II diabetes.

regulate diet/total calorie intake and exercise to ensure a balanced energy budget; low fat diet to avoid weight gain; consume complex carbohydrates to ensure gradual release of glucose into blood/avoid sudden effect on blood glucose; eat regular small meals to ensure a steady supply of glucose; do not go for long periods without meals to avoid large drop in blood glucose; consume foods (with low glycemic index) to avoid abrupt changes in blood glucose;

Distinguish between the mode of action of protein hormones and steroid hormones.

steroid hormones enter cell whereas protein hormones bind to receptors in membranes / steroid hormones can pass through cell membranes while protein hormones cannot; steroid hormones interact directly with genes/receptor proteins in cytoplasm whereas protein hormones cause release of secondary messenger in cell; steroid hormones control whether or not particular enzymes or proteins are synthesized whereas protein hormones change the cell's activity usually by activating or inhibiting enzymes;

Describe the structure of the ventilation system, including the alveoli.

ventilation occurs within the lungs; trachea divides to form two bronchi; bronchi divide to form bronchioles; several divisions of bronchioles; alveoli connected to bronchioles; trachea/bronchi/bronchioles/airways lined with cilia/ciliated epithelium; diaphragm and intercostal muscles; trachea/bronchi have rings/c-shaped pieces of cartilage; alveolus is an (air) sac; very small / diameter is (about) 100 μm; many alveoli so large total surface area; wall of alveolus is a single layer of cells; cells in alveolus wall are very thin; surrounded by a network of capillaries; some (larger) cells in the wall secrete fluid/surfactant/natural detergent;

Outline the reason for one named substance found in food not being digested and absorbed by humans.

Cellulose, the human body does not have the enzyme to digest it