BY5-June2011

Question 1

The first organisms which colonise a bare rock surface.

Answer 1

Pioneer.

Question 2

The stable stage of a succession which undergoes no further change.

Answer 2

Climax community.

Question 3

The different stages in succession.

Answer 3

Seres.

Question 4

The rate at which products such as glucose are produced by a plant.

Answer 4

Gross primary productivity.

Question 5

A diagram to represent the quantity of energy passing from one tropic level to the next.

Answer 5

Pyramid of energy.

Question 6

Give four differences between insect and wind pollinated plants.

Answer 6

Insect-large petals, brightly coloured, scented, nectar, small amount of pollen, pollen sticky/sculpted, pollen large/heavy, anthers/stigma outside flower.
Wind-small insignificant petals, dull/brown/green, not scented, no nectar, large amount of pollen, pollen smooth/non sticky, pollen small/light, enclosed within petals.

Question 7

What is the main disadvantage of self pollination?

Answer 7

Less genetic variation, increased risk of genetic faults.

Question 8

State how the production of pollen grains has enabled flowering plants to adapt to terrestrial life.

Answer 8

Pollen tube delivers make gametes to ovule/no water needed/pollen grains transferred by insects or wind.
Stops risk of dehydration of gametes.
Tough outer wall.

Question 9

Explain what is meant by the phrase ‘evolved light coats and darkly pigmented skin by natural selection’.

Answer 9

Mutation.
Variation in population.
Light coats and dark skin advantage/better adapted.
Greater chance of survival.
Passed on alleles to offspring.
Repeated over many generations.

Question 10

What is meant by the term semi-conservative replication?

Answer 10

New DNA made from an original strand linked to a new strand.

Question 11

What is the function of Sertoli cells?

Answer 11

Nutrition of sperm, supplies O2 and removes waste products.

Question 12

What are the main consequences of deforestation? Discuss methods which can be used to reduce the impact.

Answer 12

Less CO2 removed from air.
Contributes to global warming.
Consequence of global warming eg melting ice caps/flooding.
Destruction of natural habitats.
Leads to reduction in biodiversity.
Extinction of some species.
Some plants may have clinical/medicinal properties, lost before investigated.
Some species may have alleles which could be introduced into gene pool of related species.
Soil erosion, less protection of soil from drying.
Replanting.
Allow natural regeneration.
Coppicing.
Efficient forestry.
Control pests and diseases.

Question 13

The recolonisation by living organisms of a woodland following its destruction by a fire.

Answer 13

Secondary succession.