Option D

Question 1

Source of Vitamin D

Answer 1

• fatty fish
• liver
  *eggs

Question 2

Discuss exposure to sunlight as a source of vitamin B. [2]

Answer 2

• sunlight stimulates skin to synthesize vitamin D
• less sun exposure leads to skeletal deformities
• UV radiation increases incidence of skin cancer
• vegetarians more likely to lack vitamin D, need more sunlight exposure

Question 3

Outline important structural features of the outermost layer in villi. [2]

Answer 3

• microvilli to increase SA
• enzymes bound to membranes to complete hydrolysis/digestion
• tight junctions separate fluid of intestinal lumen from intercellular fluid
• large number of mitochondria as higher energy demand for active transport

Question 4

Explain the role of bile in lipid digestion. [2]

Answer 4

• bile contains bile salts
• bile salt molecules have both a hydrophilic and hydrophobic end
• emulsifies fat
• increases SA so acted on more effectively by enzyme (lipase)

Question 5

Explain why fat provides the most energy. [2]

Answer 5

• fats contain more energy than carbohydrates or proteins
• fats contain 4000 kJ per 100 g/9 kcal per 100 g

Question 6

Outline the differences in molecular structure between the types of fat. [3]

Answer 6

• saturated and unsaturated fats differ in the number of single and double C-C bonds
• saturated fat - C atoms all joined by single bonds/no double bonds
• monounsaturated fat - one double bond in carbon chain
• polyunsaturated fat - two or more double bonds in the carbon chain
• saturated fatty acid chains tend to be straight while polyunsaturated have kinks

Question 7

Explain the benefits of supplementing common foods with vitamins and minerals. [4]

Answer 7

• supplies essential nutrients lacking in diet
• benefits lower socio-economic groups as common foods are consumed by most people
• prevents nutritional deficiencies
• e.g. iodine in salt

Question 8

Outline three factors responsible for the differences in CHD death rate between two populations. [3]

Answer 8

• patient: different genetic backgrounds
• age: CHD increases with age
• smoking: smokers more prone to CHD
• diet: high saturated fat increases risk of CHD, food habits differ
• lack of exercise: sedentary vs physical lifestyle
• sex ratios: higher proportion of males will have higher rates of CHD
• alcohol consumption: alcoholics more prone to CHD

Question 9

State four glands secreting digestive juices into the alimentary canal.

Answer 9

• salivary glands
• gastric glands
• pancreas
• wall of small intestine

Question 10

Outline the function of the appetite control center in the brain. [3]

Answer 10

• sensation of being full
• stimulated by hormones (insulin, CCK) produced by pancreas/small intestine after eating
• stretch receptors in stomach after eating
• hormones (leptin) produced by adipose tissue in response to fat storage
• send message to appetite control center in brain

Question 11

Outline the circulation of blood through liver tissue. [3]

Answer 11

• hepatic artery carries oxygenated blood
• hepatic portal vein carries blood from gut/deoxygenated blood
• blood from hepatic portal vein and hepatic artery mix
• flows through sinusoids
• hepatic vein carries blood away from liver