Biology

1

100

Which term describes this plant?

Autotroph/producer

200

What is a similarity between DNA and RNA?

Both are polymers of nucleotides.

300

List two causes of variation within a gene pool.

a. sexual reproduction / random fertilization / meiosis

b. mutation

400

 What is the same in all parts of homologous chromosomes?

Sequence of genes

500

Outline energy flow through a community in a natural ecosystem.

1. communities are made up of populations of different species;
2. plants receive energy from the sun/light;
3. convert it to chemical energy through photosynthesis;
4. chemical energy is stored in organic/C-compounds;
5. the energy is passed to other organisms through feeding / reference to food chain;
6. respiration (of plants and animals) converts the chemical energy (of C-compounds) to other useful forms of energy;
7. eventually the chemical energy is lost as heat energy;
8. energy is non-recyclable/lost from a community/ecosystem;
9. energy losses between trophic levels limit food chains/mass of top trophic levels/only about 10 % of energy is transferred;

2

100

Outline the role of the enzyme helicase in replication.

unwinds/separates strands/double helix (by breaking hydrogen bonds)

200

State one cause of mutation.

radiation/mutagenic chemicals/errors in DNA replications

300

Suggest causes for the changes in ocean temperature.

 increased greenhouse effect / more heat/long wave radiation trapped in the atmosphere

400

Define mutation.

change in genetic makeup/DNA/nucleotide/base sequence

500

Explain the reasons for variation in human height.

1. environment affects height;
2. nutrition/malnutrition affects growth rate / other example of environmental factor affecting height;
3. genes/alleles affect height / height is partly heritable;
4. many possible combinations of alleles of these genes;
5. meiosis generates variation (in height);
6. mutations generate variation (in height);

3

100

In addition to carbon dioxide, which of these greenhouse gases is the most significant?

Water vapour

200

State two structural features that differ between RNA and DNA.

number of strands, base composition, uracil only in RNA / thymine only in DNA,  type of pentose, ribose only in RNA / deoxyribose only in DNA

300

What is a direct consequence of the overproduction of offspring?

 They will be subject to intraspecific competition.

400

Outline the features of ecosystems that make them sustainable.

a. recycling of nutrients/elements/components/materials ✔

b. carbon/nitrogen/another example of recycled nutrient/element ✔

c. decomposers/saprotrophs break down organic matter/release «inorganic» nutrients ✔

d. energy supplied by the sun

500

Outline the causes of sickle cell anemia.

a. genetic disease/caused by a gene OR inherited «from parents» OR caused by mutation «of a gene» ✔

b. base substitution OR GAG → GTG ✔

c. hemoglobin gene mutated / different allele/form/version of hemoglobin gene OR HbA → HbS ✔

d. leads to change in amino acid sequence «in hemoglobin» OR glutamic acid → valine ✔

4

100

At which stage of meiosis are bivalents formed?

Prophase I

200

Which level(s) of ecological complexity involve(s) biotic factors but not abiotic factors?

Community/population

300

Explain how the two strands of the DNA double helix are held together.

1. hydrogen bonding between nucleotides/bases;
2. complementary base pairs;
3. adenine-thymine and cytosine-guanine form base pairs (between the two strands with H-bonding);

400

Distinguish between the outcomes of a cell dividing either by mitosis or meiosis.

a. mitosis produces two daughter cells while meiosis four ✔

b. mitosis produces cells with same number of chromosomes (2n) while in meiosis they are halved (n) ✔

c. mitosis produces body cells but meiosis produces gametes
OR
mitosis produces genetically identical cells but meiosis does not ✔

500

What process occurs in both mitosis and meiosis?

Separation of chromatids

5

100

What distinguishes an allele from a gene?

An allele is a variety of a gene.

200

What is the name of the process that was used to produce modern corn?

Selective breeding

300

Outline natural methods of cloning in some eukaryotes.

1. asexual reproduction in plants such as tubers/runners/bulbs

2. budding in yeast/fungi

3. identical twins «in humans» are clones because they originate from the same cell

400

Outline how greenhouse gases interact with radiation and contribute to global warming.

a. carbon dioxide is a greenhouse gas 

b. methane/nitrogen oxide/water vapour is a greenhouse gas 

c. sunlight/light/(solar) radiation passes through the atmosphere (to reach the Earth’s surface) 

d. CO2 in atmosphere/greenhouse gases absorb/trap/reflect back some radiation/heat (emitted by the Earth’s surface) 

e. CO2 in atmosphere/greenhouse gases allow short wave radiation to pass (through atmosphere) but absorb long wave/infra-red 

f. solar radiation/sunlight is (mostly) short wave 

g. radiation/heat emitted by the Earth is long wave/infra-red

500

Describe the structure of the DNA molecule.

a. two stranded/double helix ✔

b. antiparallel / strands running in opposite directions

c. sugar-phosphate backbone ✔

d. each strand formed by chains of nucleotides ✔

e. each nucleotide is formed by a phosphate, a deoxyribose and a base / annotated diagram of a nucleotide clearly indicated as a nucleotide ✔

f. the bases are adenine, guanine, cytosine and thymine ✔

g. strands held together by hydrogen bonds (between complementary base pairs) OR Pairs with T and C pairs with G ✔