Topic 4 - Exam Questions

Question 1

(3 Marks)

Answer 1

~ N(N-1) -> 41 x 40 = 1640.

~ ∑n(n−1) -> 480.

~ 1640/480 = 3.42

Question 2

Answer 2

~ Gene mutation.

~ Better able to survive against selection pressure {Selection pressure mentioned}.

~ More likely to survive and reproduce, to pass advantageous allele onto the offspring.

~ Frequency of the advantageous allele increases in number, over time.

Question 3

State what is meant by the following terms: (2 Marks)

Species richness

Heterozygosity index

Answer 3

~ Species richness -> Measures number of species within a habitat.

~ Heterozygosity index -> Measure of genetic diversity within a species.

Question 4

Answer 4

~ Year 1.

~ More species present in year1, compared to year 2.

Question 5

Answer 5

~ Translocation would be stopped, transpiration stream would be prevented.

~ As the phloem contain cytoplasm within their companion cells, xylem vessels don’t have any organelles.

~ The cytoplasm contains mitochondria.

Question 6

Answer 6

~ Health workers are in close contact with people suffering from the disease.

~ Vaccination helps reduce the spread of the virus.

~ Health workers can then care for more patients.

~ Risk from the disease, is greater than the risk from the vaccine.

Question 7

Answer 7

~ Extends storage time of seeds.

~ Drying prevents growth of bacteria and fungi.

Question 8

Justify the benefits of conserving seeds (3 Marks)

Answer 8

~ Prevents species from going extinct.

~ Conserves genetic diversity.

~ Allows for reintroduction in the future.

Question 9

Describe how seeds are preserved for long periods of time in a seed bank (3 Marks)

Answer 9

~ Seeds are cleaned.

~ Seeds are stored in dry conditions.

~ Stored at cold temperatures.

Question 10

Describe the structure of a cellulose microfibril (4 Marks)

Answer 10

~ Beta glucose.

~ Glucose molecules are held together by glycosidic bonds.

~ Cellulose molecules are held via hydrogen bonds.

~ Microfibrils are composed of many cellulose molecules.

Question 11

(2 Marks)

Answer 11

~ Compare DNA sequences.

~ Compare mRNA sequences.

Question 12

(2 Marks)

Answer 12

~ J = Glycosidic bonds.

~ K = Beta glucose.