Biology 5

Question 1

Explain how the forearm acts as a lever. (3)

Answer 1

The elbow acts as a fulcrum (1). The bicep muscle contracts a short distance (1), but the radius bone acts a lever so the arm move further (1).

Question 2

Describe the causes and consequences of osteoporosis. (3)

Answer 2

There is a lack of calcium and phosphate salts in the bones of the elderly (1). This means that bones have a low density (1) so are at high risk of fractures (1).

Question 3

Why does the blood pressure vary in the arteries? (2)

Answer 3

Muscles in the ventricles contract, causing high pressure in the arteries (1). Muscles then relax so there is a low pressure (1).

Question 4

Why is the blood pressure higher in arteries than in veins? (2)

Answer 4

Muscle contractions cause high pressure in the arteries (1). Blood reduces in pressure once it travels all around the body and back in the veins (1).

Question 5

Describe common beliefs about circulation in the second and seventeenth century. (4)

Answer 5

Second C. - Heart acts as a pump (1) and blood made in the liver flows forwards and backwards (1).

Seventeenth C. - Heart has four chambers (1) and blood travels around the body in blood vessels (1).

Question 6

Suggest reasons for the present-day understanding of circulation. (2)

Answer 6

Better microscopes (1) and better technology, e.g. ECG (1).

Question 7

Explain the consequences of having a ‘hole in the heart’. (3)

Answer 7

Oxygenated blood mixes with de-oxygenated blood (1) so less oxygen in blood which travels around the body (1). Blood pressure is lower as blood can flow directly into the right ventricle (1).

Question 8

Babies born with a ‘hole in the heart’ are called blue babies. Explain why. (2)

Answer 8

Blood contains less oxygen (1) so is not bright red (1).

Question 9

Explain the importance of physical digestion. (3)

Answer 9

Physical digestion breaks food so it has a larger surface area (1) for enzymes to act on (1). This allows food to travel through the digestive system easily (1).

Question 10

Which food molecules are absorbed into the blood plasma? (2)

Answer 10

Glucose (1) and amino acids (1).

Question 11

Which food molecules are absorbed into the lymph? (1)

Answer 11

Fatty acids (1).

Question 12

Describe the break down of starch. (4)

Answer 12

Starch is a complex polymer (1) which is broken down into maltose -double sugar - (1). Maltose is further broken down into glucose - single sugar - (1) using different carbohydrase enzymes (1).

Question 13

Explain the role of a negative feedback mechanism in regulating the concentration of urine. (4)

Answer 13

Negative feedback correct a change (1). The concentration of urine is controlled by ADH (1). ADH is no longer secreted when the concentration in the blood increases (1). This means less water is reabsorbed and urine is dilute (1).

Question 14

Explain how negative feedback controls levels of oestrogen. (3)

Answer 14

When oestrogen levels are high, negative feedback reduces FSH levels (1). This means that egg follicles are not stimulated (1) and oestrogen is not released (1).

Question 15

What are the main problems to the recipient after receiving a transplant? (2)

Answer 15

Rejection (1) and taking immunosuppressive drugs for a life time (1).

Question 16

Suggest why heart and lung transplants are uncommon. (3)

Answer 16

It is a complex procedure (1) which is high risk (1) and rejection can result in death (1).

Question 17

Describe the process of ossification. (4)

Answer 17

Cartilage is replaced by bone (1) by converting it to calcium and phosphate salts (1). Some cartilage remains for further growth (1) and some remains at the end of bones (1).