4th Form Exam Review

Question 1

why do Lactobacillus cells not burst when placed in distilled water?

Answer 1

• they have a cell wall which maintains structure
• water enters via osmosis
• because the water potential inside the cell is lower

Question 2

how does Lactobacillus produce yoghurt from milk?

Answer 2

• Lactobacillus digests the milk
• converts lactose into lactic acid
• thickens the yoghurt
• using respiration/fermentation

Question 3

what are the enzymes that breaks down protein?

Answer 3

• protease
• pepsin (in stomach)

Question 4

how does trophic level affect amount of energy an animal receives?

Answer 4

• shorter food chain increase the amount of energy recieved
• energy is lost through excretion/respiration/movement etc.

Question 5

how can a student modify the yeast experiment to give more accurate results?

Answer 5

• correct volume of gas
• using a measuring cylinder/syringe

Question 6

what is the process of nitrogen gas to nitrogen in organic molecules?

Answer 6

nitrogen fixation

Question 7

what is the process of nitrites to nitrates?

Answer 7

nitrification

Question 8

what is the process of nitrate to nitrogen gas?

Answer 8

denitrification

Question 9

why are plants placed in the dark 24 hours before investigating the effect of light on photosynthesis?

Answer 9

so that the leaves are de-starched

Question 10

what is the CORMS experiment of investigating how sunlight affects the size of the leaves of plants?

Answer 10

C - plant in shaded and unshaded
O - same species/type/age