Biology MCQ

Question 1

What is the role of cholesterol in cell surface membranes?

Answer 1

cholesterol binds to the HYDROPHOBIC phospholipid FATTY ACID TAILS, increasing the packing of the membrane, therefore REDUCING the fluidity of the membrane

Question 2

What are conjugated proteins?

Answer 2

globular proteins with a non-amino acid component associated with it e.g. - lipoproteins (protein + lipid) - glycoproteins (protein + carb) - haemoglobin (protein + Fe2+) - catalase (protein + Fe2+)

Question 3

An investigation into how a change in NaCl concentration affects osmosis in potato cells concluded that the isotonic point of the potato was 0.25M - what happens at the isotonic point?

Answer 3

the movement of water INTO the potato cells is EQUAL to the movement of water OUT of the potato cells.

Question 4

Factors affecting enzyme function/shape?

Answer 4

• denatured at high temp - molecules move slow at low temp - H-bonds (denatured) break if pH outside optimum - non-competitive inhibitor - binding of fit (induced fit)

Question 5

A chemical produced by a metabolic pathway binds to the initial enzyme in the pathway; the chemical binds to the enzyme at a site away from the active site & inhibits enzyme action - why?

Answer 5

• it is an end product inhibitor - it binds to the allosteric site of the enzyme (it is NOT a competitive inhibitor)

Question 6

Which of the following statements describes a feature of peritoneal dialysis?

Answer 6

• (only 1) - urea and mineral ions pass into the tissue fluid

Question 7

Guanine is synthesised from ammonia in the liver - why do birds excrete guanine?

Answer 7

• ammonia is more toxic than guanine - urea is more soluble in water than guanine - guanine has a high proportion of nitrogen

Question 8

The drug metoprolol prevents stimulation of post-synaptic receptors in the sympathetic nervous system. - which of the following conditions could be treated using this drug? (1) muscle fatigue (2) tachycardia (3) high blood pressure

Answer 8

(2) tachycardia & (3) high blood pressure

Question 9

Animals receive different stimuli from their environment; their synapses can manage multiple stimuli often resulting in one response - this action of the synapse is an example of:

Answer 9

spatial summation

Question 10

see table.

Answer 10

• spatial summation

Question 11

What are the 3 domains of life?

Answer 11

• archaea
• bacteria
• eukaryota

Question 12

Where does ultrafiltration take place?

Answer 12

• in the Bowman’s capsule

Question 13

How does ultrafiltration take place?

Answer 13

• involves hydrostatic pressure (created due to the difference in diameter of the afferent & efferent arterioles
• all small molecules are forced out
• filtering system involves capillary wall, basement membrane & wall of the Bowman’s capsule
• basement membrane is comprised of collagen & protein; it acts like a sieve, blood cells & large proteins that made it this far can’t get through

Question 14

ultrafiltration filtrate contains:

Answer 14

• glucose
• salt
• water
• urea
• inorganic ions (same conc. as in plasma)
  approx. 20% of material in the blood is filtered through the capsule; most needs to be reabsorbed

Question 15

why does diastole follow systole in the mammalian heart?

Answer 15

• cardiac mucle takes a short time to repolarise after being stimulated

Question 16

what valves are responsible for the lub sound in the lub dub of the heart?

Answer 16

• closing of the atrioventricular valves

Question 17

see diagram.

Answer 17

0.2-0.3s

Question 18

Biologists use both phylogeny & classification to understand how different species are related - give an example of phylogeny

Answer 18

• homo sapiens & pan bonobo share a common ancestor

Question 19

many plants are adapted to the availability of water in their environment - what correctly describes a xerophyte?

Answer 19

• the poison tree has leafless branchess covered in thorns to reduce water loss

Question 20

what is not an adaption to reduce water loss in plant?

Answer 20

• an extensive root system that extends far from the plant