paper 2 exam questions Flashcards
describe how stomata open (3 marks)
guard cells take in water via osmosis
why use a leaf peel rather than a whole leaf on a microscope? (2 marks)
- leaf peel is thin while whole leaf is too thick
- light is able to shine through thin leaf peel to identify the stomata
describe a method to see how much tissue from an artery can stretch before no longer returning to original size (3 marks)
- measure initial length of tissue
- add masses
- remove mass and measure length of tissue to see if it returns to original size
- repeat until tissue no longer returns to original length
explain why it is an advantage to have no stomata in the upper surface of the leaf (2 marks)
no stomata reduces water loss during transpiration/evaporation
why is there a decrease in blood flow to the digestive system during exercise? (2 marks)
- increased blood flow to the muscles and restricted blood flow to other parts of the body
- to allow for more respiration
explain why the body temperature of the iguana affects its oxygen consumption (3 marks)
- chemical reactions in the body are increases at higher temperatures
- more respiration occurs which requires more oxygen
explain the role of vasodilation in thermoregulation (4 marks)
- vasodilation cools the body down
- more blood flows to the skin surface
- less blood flows through the shunt valve
- causing more thermal energy loss
another method (other than measuring change in length) to show growth of seedlings (1 mark)
measure change in mass
why do farmers use leguminous plants in their crop rotation cycle (3 marks)
- nitrogen-fixing bacteria live on root nodules of leguminous plants
- they produce ammonia/nitrates from atmospheric nitrogen
- increases nitrate/ammonia levels in the soil
why are women over the age of 50 less likely to ovulate (2 marks)
- women have low levels on oestrogen
- oestrogen is needed for LH to be released
- LH is need for ovulation to occur
why are women over the age of 60 less likely to menstruate (2 marks)
low levels of oestrogen stops uterus lining building up so there is no lining to be lost by a period
how does the release of adrenalin result in the improved performance of an athlete (4 marks)
- adrenalin increases heart rate
- increased blood flow
- more oxygen transported to cells
- increased rate of respiration
- more energy released for muscles
how is marram grass adapted to survive in hot, windy and dry conditions (6 marks)
- thick waxy cuticle prevents water loss by evaporation
- grass is flexible so does not break in windy conditions
- long thin leaves reduces air resistance
- no stomata on upper surface prevents water loss
- hairs on the lower surface reduce air movement
describe a method to estimate the population of slugs in a garden (3 marks)
- use a quadrat
- count the number of slugs in the sampled area
- multiplication factor to make the estimate
explain why cellular respiration is essential for living organisms (2 marks)
to release energy for metabolic purposes
