IB Biology Option D

Which of the following is true of vitamin D?

• It causes rickets

• It promotes calcium absorption in the gut

• Skin cells produce more of it in the winter than in the summer

• Humans cannot make it due to lacking the necessary enzyme

Which of the following are true of vitamin D?

I. It is absorbic acid

II. Oily fish are a good source of it

III. A deficiency of it can cause an enlarged liver

• I and II only

• I and III only

• II and III only

• I, II and III

Which of the following are true of vitamin C?

I. It is needed to make collagen

II. A deficiency of it can cause scurvy

III. Humans cannot make it due to lacking the necessary enzyme

• I and II only

• I and III only

• II and III only

• I, II and III

Which of the following are symptoms of a deficiency in vitamin C?

I. Skin discolouration and bruising

II. Anaemia

III. Loosened teeth and bleeding gums

• I and II only

• I and III only

• II and III only

• I, II and III

If a person has phenylketonuria (PKU), which enzyme cannot be produced?

• phenylalanine hydrolase

• phenylalanine hydroxylase

• tyrosine hydrolase

• tyrosine hydroxylase

Which of the following would be expected if a baby with PKU is left untreated after birth?

I. a high level of tyrosine in the blood

II. mental retardation

III. a high level of phenylalanine hydroxylase in the blood

• I only

• II only

• III only

• I, II and III

Which of the following is not true of phenylketonuria (PKU)?

• An untreated person with PKU will have a high level of phenylalanine in the blood

• It is caused by a gene mutation

• An child with PKU will show symptoms before birth

• Phenylalanine is an essential amino acid

Which of the following could be involved in treating a person who has phenylketonuria (PKU)?

I. a diet low in phenylalanine

II. supplements of tyrosine

III. a protein-rich diet

• I and II only

• I and III only

• II and III only

• I, II and III

Which of the following is not true of the cholera toxin?

• It is produced by the virus Vibrio cholerae

• It attaches to receptors on intestine cells

• It enters the cell by endocytosis

• It causes Cl^- and HCO₃^- ions to enter the intestine lumen

In cholera, what causes the faeces to contain such a high concentration of water?

• Cl^- and HCO₃^- ions move into the blood and decrease its solute potential

• Cl^- and HCO₃^- ions move into the blood and increase its solute potential

• Cl^- and HCO₃^- ions move into the intestine lumen and decrease its solute potential

• Cl^- and HCO₃^- ions move into the intestine lumen and increase its solute potential