Explanation:
Choice A is correct because during metaphase I homologous chromosomes align at the equator and are subject to random orientation. Choice B is incorrect as, during Prophase I, homologous chromosomes condense and crossing over occurs. Choice C is incorrect as, during Metaphase II, chromosomes align on the cell's equator, and there is random orientation of the sister chromatids and not homologous chromosomes. Choice D is incorrect as, during Prophase II, chromosomes align on the cell's equator.

Explanation​:
The nuclear envelope is the membrane that separates the nucleus from the cytoplasm. For mitosis to proceed it must be broken down in the first stage of mitosis which is prophase so that the spindle fibres are able to attach to the centromeres. Choice A is correct.

Metaphase (Choice B), Anaphase (Choice C) and Telophase (Choice D) all follow Prophase (Choice A) in the sequence of mitosis and do not involve the breakdown of the nuclear envelope.

Explanation​:
If there are two alleles for a gene, but there are three possible phenotypes, this could suggest incomplete dominance (Choice C). This is when the dominant allele doesn’t completely suppress the effects of the recessive allele. Choice A is incorrect because if one allele was completely dominant over the other, then there would only be two possible phenotypes. Choice B is incorrect because if the alleles were codominant, then we would see both expressed in the phenotype. In this case, some petals would be white and others red, instead of the flower being pink. Choice D is incorrect because sex-linkage does not create an additional phenotype.

Explanation​:
Choice B is correct because there are pairs of homologous chromosomes lined up on the equator, and each chromosome is attached to only one pole. Choice A is incorrect because in metaphase II, chromosomes are not in homologous pairs. Each chromosome, composed of sister chromatids, is attached to both poles. Choice C is incorrect because in anaphase I, homologous chromosomes are separated, and one chromosome from each pair is pulled to one pole. Choice D is incorrect because in telophase I, there are two sets of chromosomes that are already separated.

Explanation​:
Protein pumps are membrane proteins that carry out active transport. They require the energy to pump molecules up their concentration gradient.

Protein channels (Choice A), protein carriers (Choice C), and aquaporins (Choice D) all conduct passive transport.

Explanation​:
Choice C is correct because the biological mother passes on the X chromosome to a son and the biological father contributes only with Y. For the son to be colour-blind, he must have an allele for it on the X chromosome. Therefore the biological mother must have at least one recessive allele (n). Choices A and B are incorrect because individuals with X and Y are male. Choice D is incorrect because, in this case, no sons would have the condition.

Explanation:
The fossil record provides evidence of evolution, as the sequence in which fossils appear matches the sequence that they would be expected to evolve. Homologous structures provide evidence of evolution as they provide evidence that organisms shared a common ancestor. Speciation provides evidence of evolution as when populations become reproductively isolated, then natural selection can act differently on those populations, resulting in the formation of new species. Choice C is correct. Choices A and D are incorrect as the organisms becoming more complex does not necessarily correlate with evolution. Choice B is incorrect, as the increasing size of organisms does not necessarily correlate with evolution.

Explanation:
A greenhouse gas is a gas that contributes to the greenhouse effect. Greenhouse gases absorb the long wave infrared radiation (heat energy) emitted from Earth’s surface and can reradiate it back to Earth’s surface. So, one factor that determines whether a gas acts as a greenhouse gas is its ability to absorb long wave radiation: gases that are better able to absorb long wave radiation are more likely to act as greenhouse gases. A second factor that qualifies carbon dioxide as a greenhouse gas of concern is its relatively high concentration in the atmosphere: gases that are in higher concentration in the atmosphere have a larger effect on Earth’s temperature.

Explanation:
Sexual reproduction results in variation as it is the fusion of genetically distinct gametes from two genetically different individuals. Mutation results in variation as it produces new alleles. Meiosis results in variation as it produces new combinations of alleles. Choice C is correct.

Choices A, B and D are incorrect as they all include either mitosis, asexual reproduction or binary fission, which all produce genetically identical cells.

Explanation​:
A mRNA strand contains four nitrogenous bases: adenine (A), cytosine (C), guanine (G) and uracil (U). It does not contain thymine (T) (Choice C and Choice D).

Most mRNA strands which code for polypeptides begin with the $\text{‘}$START$\text{’}$ codon AUG and end with a `STOP$\text{’}$ codon, UAG, UAA or UGA (Choice A). Choice B has a $\text{‘}$STOP$\text{’}$ codon at the beginning which would terminate translation before it begins.

Explanation​:
Choice C is correct, as the 9th nucleotide in the sequence (C) has been deleted from the original sequence.

Choice A is incorrect as it is the exact same sequence as the original sequence. Choice B is incorrect as it represents an insertion mutation, an adenine has been inserted in the 7th position. Choice D is incorrect as it represents a base substitution mutation, as G has replaced a T in the 14th position.

Explanation​:
Peptide bonds form between amino acids as a result of condensation reactions. Statement II (Choice C) is correct because dipeptides are composed of two amino acids held together by a peptide bond and proteins (Statement III) are composed of one or more polypeptides, which are chains of amino acids held together by peptide bonds. Choice A, B and D are incorrect as individual amino acids (Statement I) do not possess peptide bonds.

Explanation​:
Telophase is the last phase of mitosis and does not cause mutations (Choice C). Single base substitutions cause a change in the base sequence of DNA, which is a mutation (Choice A). Carcinogens (Choice B) and high energy radiation (Choice D) are mutagens which means they can cause changes in the base sequence of DNA.

Explanation​:
Choice A, B, and D – These statements are true.

Choice C -This statement is false. In eukaryotic cells, translation takes place in the cytoplasm. Prokaryotic cells do not have a nucleus.

Explanation​:
Choice B is correct because pollination is the transfer of pollen from an anther to a stigma. Choice A is incorrect because the fusion of a male and female gamete is fertilization. Choice C is incorrect because the transfer of seeds away from the parent plant is dispersal. Choice D is incorrect because pollination can occur without a pollinator. Some plants are wind-pollinated.

Explanation:
A base substitution is when one nucleotide randomly replaces another in a sequence causing a single nucleotide polymorphism. This can result in a shorter polypeptide being translated (Statement I) due to the base change causing a stop codon to appear earlier in the DNA/mRNA sequence. It can also cause an altered polypeptide chain to be translated (Statement II) if the base substitution causes a different amino acid to be translated. It can also have no effect on the polypeptide that is translated (Statement III), as the genetic code is degenerate, meaning many codons code for the same amino acid. Choice D is therefore correct.

Choices A, B and C are incorrect, as they do not include all three statements.

Explanation:
Facilitated diffusion and osmosis are both passive means of transport and therefore do not require energy.

Active transport (Choice A) requires energy expenditure. Facilitated diffusion is a passive form of transport but active transport requires energy (Choice B). Facilitated diffusion (Choice D) does not require energy expenditure but this answer choice does not include osmosis.

Explanation​:
Choice C is a correct definition of a gene. Chromosomes are made of DNA and protein (Choice A), while genes are only made of DNA. When DNA is at various levels of supercoiling, it is wrapped around histone proteins. However, the presence of histones is not part of the definition of a gene (Choice B). Genes control some characteristics, but some characteristics are also affected by the environment (Choice D).

Explanation:
Choice D is correct because food is stored in the cotyledon(s). Choice A is incorrect because the function of the radicle is to develop into the root of the seedling. Choice B is incorrect because the function of the plumule is to develop into the shoot of the seedling. Choice C is incorrect because the testa is the outer covering of the seed.

Explanation​:
mRNA, also known as messenger RNA, carries the genetic information needed for protein synthesis (Choice B).

Ribosomal RNA is found in ribosomes. This RNA contributes to the structure of the ribosome and does not code for proteins (Choice A).

ATP (Choice C) is a molecule made out of a nucleotide (adenosine tri-phosphate), while nucleic acid is made out of many nucleotides.

tRNA (Choice D), also known as transfer RNA, brings amino acids to the ribosomes and does not code for proteins.

Explanation​:
Choice A is correct because pollen is produced by the anther and the ovum (plural: ova) is produced by the ovule, found inside the ovary. Choice B is incorrect because the stigma is where pollen lands. Choice C is incorrect because the filament supports the anther and does not produce pollen. Choice D is incorrect because the filament supports the anther and the style is the part of the flower that the pollen passes through.

Explanation​:
Mitosis forms two genetically identical daughter cells with the same number of diploid chromosomes as the parent cell.

18 (Choice B) is incorrect as it is the haploid number of chromosomes. 72 (Choice C) is incorrect as it is twice the diploid number of chromosomes. 9 (Choice D) is incorrect as it is a quarter of the diploid number and an odd number.

Explanation​:
The question states that heterozygous individuals have the banded pattern on their hairs, which means that the agouti trait is dominant. Two heterozygous parents will produce offspring with the dominant and recessive characteristics in the ratio of 3:1 (Choice B). The offspring of a heterozygous individual and a homozygous agouti individual will all receive at least one dominant allele, so they would all be agouti (Choice A). The offspring of at least one parent that is homozygous for agouti will all have the agouti characteristic (Choices C and D).

Explanation​:
Choice A is correct because high blood glucose concentration is detected by the beta cells in the pancreas and they respond by releasing insulin. Choice B is incorrect because alpha cells produce glucagon and not insulin. Choice C is incorrect because the release of insulin is triggered by high blood glucose concentration and not low blood glucose concentration. Choice D is incorrect because low blood glucose concentration does not cause the release of insulin and insulin is not secreted by alpha cells.

Explanation​:
PCR is used to amplify samples of DNA so they can be used for analysis.

PCR replicates DNA but does not show that replication is semi-conservative (Choice A).

PCR does not determine the base sequence of DNA. It produces copies of short sections of DNA that can then be further analyzed (Choice B).

Taq polymerase is an enzyme used in PCR but no Taq DNA is incorporated. (Choice D).