biodiversity and classification

Question 1

What is a species?

Answer 1

. Group of similar organisms / organisms with similar features / / organisms with same genes / chromosomes;
. Reproduce to produce fertile offspring;

Question 2

What is a community?

Answer 2

. All the individuals;
. Of all the species;
. Living together in the same area;
. At the same time;

Question 3

Explain what is meant by a hierarchy.

Answer 3

. Groups within groups;
. No overlap (between groups);

Question 4

Explain what is meant by a phylogenetic group.

Answer 4

. (Grouped according to) evolutionary links/history/relationships / common ancestry;

Question 5

Explain what is meant by genetic
diversity.

Answer 5

. Difference in DNA/base sequence/alleles/genes;

Question 6

What information is required to calculate an index of diversity for a particular community?

Answer 6

. Number of species;
. Number of individuals in each species;

Question 7

The number of species present is one way to measure biodiversity.
Explain why an
index of diversity may be a more useful measure of biodiversity.

Answer 7

. Also measures number of individuals in a species / different proportions of species;
. Some species may be present in low/high numbers;

Question 8

Give 2 advantages of using an index of biodiversity rather than an indicator species

Answer 8

. You do not need to identify each species;
. Index consider the number of organisms of each of the species;

Question 9

What is meant by species richness?

Answer 9

The number of different species in a community

Question 10

Explain how natural selection produces changes within a species.

Answer 10

. Variation [caused by mutation] between members of population / species;
. Predation / disease / competition results in differential survival;
. Some have adaptations that favour survival;
. Differential reproductive success / survive to reproduce/ have more offspring/
. Pass on their advantageous alleles /
. Changes allelic frequencies

Question 11

Describe how comparisons of biological molecules in two species could be used to find out if they are closely related.

Answer 11

Genetic variation:
. Compare DNA base sequence;
. Compare RNA base sequence;
. Compare sequence of amino acids /primary structure (of named / same protein);

DNA hybridisation:
. By separating DNA strands / break hydrogen bonds;
. Mix DNA/strands (of different species);
. Temperature/heat required to separate (hybrid) strands indicates relationship;

Immunological evidence – not a mark:
. Inject (seahorse) protein/serum into animal;
. (Obtain) antibodies/serum;
. Add protein/serum/plasma from other (seahorse) species;
. Amount of precipitate indicates relationship;

Question 12

In classification, comparing the base sequence of a gene provides more information than comparing the amino acid sequence for which the gene codes. Explain why.

Answer 12

. Reference to base triplet/triplet code / more bases than amino acids / longer base sequence than amino acid sequence;
. Introns/non-coding DNA;
. Same amino acid may be coded for / DNA code is degenerate;

Question 13

Scientists’ analysis of blood proteins has indicated a lack of genetic diversity in populations of some organisms.
Describe the processes that lead to a reduction in the genetic diversity of populations of organisms. (6)

Answer 13

1. Mark for general principle of - reduced variety/number of different alleles/DNA / reduced gene pool (in new population);
2. Founder effect;
3. A few individuals from a population become isolated/form colonies:
4. (Genetic) bottlenecks;
5. (Significant) fall in size of population
6. Selective breeding / artificial selection;
7. Using organisms with particular alleles / traits / phenotypes / characteristics

Question 14

Scientists can use protein structure to investigate the evolutionary relationships
between different species.
Explain why.

Answer 14

. Amino acid sequences / primary structure;
. Closer the (amino acid) sequence the closer the relationship;
. (Protein structure) related to (DNA) base/triplet sequence;

Question 15

A forest was cleared to make more land available for agriculture.
After the forest was cleared the species diversity of insects in the area decreased.
Explain why. (4)

Answer 15

. Decrease in variety of plants / fewer plant species;
. Fewer habitats/niches;
. Decrease in variety of food / fewer food sources;
. Aspect of clearing forest (killing insects) eg machinery, pesticides;

Question 16

What is meant by a genetic bottleneck.

Answer 16

. Sudden decrease in population / many killed by an event eg earthquake;
. Idea of reduced/low genetic variation/diversity / reduction in (variety of) alleles / smaller gene pool;

Question 17

Suggest one ethical argument for maintaining biodiversity.

Answer 17

. Prevent extinction /loss of populations/ reduction in populations /loss of habitats / save organisms for future generations (idea of);

Question 18

Suggest one economic argument for maintaining biodiversity.

Answer 18

A suitable example of how some species may be important financially e.g.
. medical / pharmaceutical uses;
. commercial products / example given;
. tourism;
. agriculture;
. saving local forest communities;

Question 19

Farmers clear tropical forest and grow crops instead. Explain how this causes the
diversity of insects in the area to decrease.

Answer 19

. Lower diversity of plants/ few species of plants/less variety of plants/few plant layers;
. Few sources/types of food/feeding sites;
. Few habitats/ niches;
. Fewer (species of) herbivore so few (species of) carnivores;
. Aspect of agriculture (killing insects);

Question 20

Describe how courtship behaviour increases the probability of successful mating.

Answer 20

. Attracts/recognises same species;
. Attracts/recognises mate/opposite sex;
. Indication of sexual maturity/ fertility / synchronises mating;
. Stimulates release of gametes;
. Form pair bond;