Year 12 Homework Retrieval Practice 1

Question 1

Describe how injection of antigen in a vaccination produces immunity

Answer 1

1. Vaccines contain antigens as dead or weak pathogens
2. A specific immune response takes place
3. Memory cells are made
4. On second exposure, memory cells produce plasma cells quickly and in large numbers
5. Plasma cells rapidly produce antibodies
6. Antibodies destroy pathogens
7. Herd immunity occurs - fewer people to pass on disease

Question 2

Draw a diagram to compare antibody production in the primary and secondary response

Answer 2

Question 3

Give and explain the 3 differences between active and passive immunity

Answer 3

Active involves the production of antibodies by plasma cells and results in production of memory cells, whereas in passive, antibodies are introduced into the body from outside sources, e.g. given by mother or antiserum

Active is long term because antibodies and memory cells are produced in response to the antigen, so the secondary response will occur if the pathogen is met again. However, passive is short term because the antibodies given will be broken down by the body

Active is slow acting as it involves clonal selection and clonal Expansion which takes time, but passive is fast acting because it doesn’t.

Question 4

Compare and contrast the structure of the walls of arteries and veins in relation to their function (2 similarities and 5 differences)

Answer 4

Similarities:
1) they both have inner endothelium which is smooth and reduces friction
2) they both contain some elastic tissue

Differences:
1) the artery has lots of elastic tissue to stretch under high pressure and recoil, maintaining a constant pressure. However, the vein doesn’t have as much elastic tissue as the pressure is lower

2) the artery has a thicker wall than veins because it has a higher blood pressure

3) veins have large lumen which reduce the resistance, causing a lower blood pressure, compared to the artery which has a smaller lumen to maintain a higher blood pressure

4) arteries have lots of smooth muscle for vasoconstriction, veins do not have lots of smooth muscle

5) veins have valves to prevent backflow of the low pressure blood, but most arteries do not have valves ( exception is the pulmonary artery and aorta)

Question 6

Name the blood vessels which supplies blood to the heart muscle

Answer 6

Coronary arteries

Question 7

Explain the cardiac cycle

Answer 7

1) Atrial systole:
- the atria contract simultaneously to force blood into the ventricles.
- this increases the pressure in the atria above that of the ventricles, causing the atrioventricular valves to open
- the blood flows out of the atria into the ventricles

2) Ventricular Systole:
- The atria relaxes, the ventricles contract from the base up and force the AV valves shut (lub), to stop the blood from flowing back,
- the ventricles continue to contract and open the semilunar valves, and blood leaves the heart via the aorta and pulmonary artery.
- the pressure in the ventricles increases above that of the atria, forcing the AV valves shut so backflow can’t happen,

Diastole:
- The ventricles relax, and the semilunar valves shut (dub).
- The AV valves open and the whole heart fills with blood.

Question 8

Describe how tissue fluid forms

Answer 8

1) There is a high hydrostatic pressure at the arterial end of the capillary, due to the contraction of the left ventricle. The hydrostatic pressure is higher than the osmotic pressure pushing the tissue fluid back into the capillaries.

2) this forces water and other dissolved substances out of the capillary.

3) the hydrostatic pressure falls from the arteriole end of the capillary to the venule end of the capillary, due to this loss of water and also due to friction against the endothelium lining

4) when the water leaves the capillary, plasma proteins are too large to leave the capillary. This increasing concentration of blood proteins reduces the water potential of the blood, which causes the water potential of the blood plasma to increase from the arterial end to the venous end of the capillaries. This high water potential causes water to move back into the capillary by osmosis.

Any tissue fluid not re-absorbed by the venule end of the capillary must be absorbed into the lymphatic system and returned to the circulation at the subclavian vein.

Question 9

How does high blood pressure effect tissue fluid

Answer 9

High blood pressure (hypertension) leads to an accumulation of tissue fluid (oedema).

How this happens:
- high blood pressure means there’s a high hydrostatic pressure, which increases the outward pressure from the arteriole end of the capillary (and reduces the inward pressure at the venule end of the capillary). Therefore, more tissue fluid is formed and less can be reabsorbed. The lymphatic system is not able to drain the excess fast enough

Question 11

Explain why starving causes tissue swelling

Answer 11

This causes a reduction in plasma proteins, meaning it can’t reduce the water potential as much as water. This reduces the water potential gradient between the blood and the tissue, so less tissue fluid is reabsorbed at the Venus end of the capillary

More fluid in tissues causes swelling

Question 12

How does an enzyme lower activation energy

Answer 12

By selling reactants and stressing bonds

Question 13

Draw an ATP molecule

Answer 13

Question 14

Describe how insects exchange gases with the environment

Answer 14

Via tracheal system - because they use up oxygen for respiration and release carbon dioxide, this creates a concentration gradient with a high concentration of carbon dioxide and low concentration of oxygen in the bug,

Oxygen diffuses from the air outside through small holes called spiracles and down the trachea. The tracheoles transport the oxygen gas to all tissues.

Respiration occurs in the cells of respiring tissue and carbon dioxide is produced. The carbon dioxide diffuses from tissues down the tracheoles, down the trachea and out of the spiracles into the air

Question 16

What is the role of the enzyme ATP hydrolase

Answer 16

Hydrolyses ATP to adenosine diphosphate (ADP) and an inorganic phosphate group (Pi).

Question 17

What is the hydrolytic enzyme within lysosomes called

Answer 17

Lysozymes

Question 18

Define the term antigen

Answer 18

A foreign protein which causes a specific immune response which results in the production of specific antibodies

Question 19

What is the term to describe the formation of an antigen - antibody complex

Answer 19

Agglutination

Question 20

Draw and label a nucleotide

Answer 20

Question 21

What do monoglycerides, fatty acids and bile salts make

Answer 21

Micelles

Question 24

Give the formula for rate of diffusion

Answer 24

a means proportional

Question 25

Describe the fish gill anatomy

Answer 25

Question 26

Give 3 adaptations fish have to ensure efficient gas exchange

Answer 26

1) large surface area to volume ratio, which is created by many gill filaments which are covered in many gill lamellae 2) short diffusion distance due to the network of capillaries in the thin lamellae being very close to the surface 3) a concentration gradient is maintained by the countercurrent flow mechanism

Question 27

Explain how the countercurrent exchange principle works in fish

Answer 27

Water flows over the gills in the opposite direction to the flow of blood in the capillaries, This ensures that equilibrium is not reached, ensuring a diffusion gradient is maintained across the ENTIRE length of the gill lamellae

Question 28

Describe and explain three structural features that reduce the rate of transpiration in xerophytic plants

Answer 28

1) rolled leaves- traps air which becomes saturated, and reduces the water potential gradient between the air and the leaf. Also reduces surface area. These both mean less water diffuses across the stomata 2) thick cuticle - increases diffusion distance 3) sunken stomata - reduces air movement across stomata and traps air which becomes saturated, reducing the water potential gradient, less water leaves stomata 4) hairs trap air which becomes saturated 5) reduced number of leaves- less surface area, fewer stomata so less water evaporates out. 6) guard cells open and close, water can't leave when they're closed

Question 29

Give the equation for breathing rate

Answer 29

Pulmonary ventilation rate = tidal volume × breathing rate

Question 30

Describe how a red blood cell is adapted to its function (3)

Answer 30

Biconcave shape - larger surface area to volume ratio to increase rate of diffusion of oxygen into cells No nucleus - makes more space for haemoglobin Thin - short diffusion distance to increase rate of diffusion into cells

Question 31

What causes the production of tissue fluid at the capillary bed

Answer 31

At the artery end of the capillaries, hydrostatic pressure is higher than the opposing water potential gradient, so fluid and dissolved substances are forced out of the capillary

Question 32

What causes the reabsorption of tissue fluid at the capillary bed

Answer 32

Towards the Venus end of the capillaries,distance from the heart increases so blood pressure decreases, decreasing the hydrostatic pressure. The plasma proteins are too large to move out of the capillary, so water potential in the capillary is lower than in the surrounding tissue. This means the hydrostatic pressure is lower than the opposing water potential gradient, so water moves into the capillary by osmosis with the dissolved substances. The lymph vessel absorbs excess tissue fluid, and returns it to the circulatory system.

Question 33

Describe how you would test a liquid sample for the presence of a protein

Answer 33

Add the biuret solution to a test tube with the sample and wait 5 minutes The solution will change from blue to purple if protein is present

Question 34

What type of bonds form between nucleotides during a condensation reaction

Answer 34

Phosphodiester bonds