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:
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:
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:
Choice A is incorrect because urea is reabsorbed.

Choice B is correct because all glucose is reabsorbed by the proximal tubule, none is reabsorbed by the distal convoluted tubule.

Choice C is incorrect because water is reabsorbed by the distal convoluted tubule.

Choice D is incorrect because Na+ ions are reabsorbed by the distal convoluted tubule.

Explanation:
Choice D is correct because there are four chromosomes, and each chromosome is composed of sister chromatids. Choice A and choice C are incorrect because, in metaphase, chromosomes are lined up on the equator. Choice B is incorrect because, during anaphase II, chromosomes are being pulled apart and towards opposite poles.

Explanation:
Choice B is correct because, in a healthy kidney, white blood cells are too large to pass from the glomerulus into the Bowman’s capsule. Choices A, C and D are incorrect because amino acids, water and glucose are small enough to be filtered from the capillaries in the glomerulus into the Bowman’s capsule.

Explanation:
Choice B is correct because a meristem is a part of a plant with undifferentiated cells that undergo cell division. Choice A is incorrect because meristems do not have differentiated cells that undergo cell division. Choice C is incorrect because a meristem is not defined as a region of a flower. Choice D is incorrect because cell division in a meristem is not influenced by day length.

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:
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:
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).

Explanation:
Choice A is correct because when there are fewer copies of a given strand of mRNA in the cytoplasm, ribosomes have fewer copies to bind to and thus the rate polypeptides are synthesised based on this strand will decrease, not increase (Choice B).

Choices C and D are incorrect because if the rate mRNA is degraded decreases, there will be more copies of this strand of mRNA resulting in an increase in the rate ribosomes bind to these strands and synthesise polypeptides.

Explanation:
Choice A is incorrect as autosomes are chromosomes that are not the sex chromosomes and so do not determine biological sex. Choice B is incorrect as linked genes are genes that are found on the same chromosome. Choice C is incorrect as a gene locus is the position of a gene on a chromosome.

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.

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:
Choices A, B and D are all incorrect as they all cause changes to allele frequency.

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:
Nitrogen makes up approximately 78% of dry air and is not a greenhouse gas.

All other gases when present in the air enhance the greenhouse effect to cause global warming. (Choices A, B and C)

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:
Choice B is correct because human males have one X chromosome and one Y chromosome. Choice A shows the sex chromosomes of a female. Choice D only shows the Y chromosome, which is incorrect because males have an X and a Y chromosome. Choice D only shows the X chromosome, which is incorrect because males have an X and a Y chromosome.

Explanation:
The bond formed between two glucose molecules to form maltose is an alpha 1-4 linkage. This is a covalent bond between two alpha glucose molecules, where the carbon #1 of one of the glucose molecules forms a bond with the carbon #4 of the other glucose molecule. Choice C is correct.

A hydrogen bond (Choice A) is a weak electrostatic attraction between a hydrogen atom that is covalently bonded to a highly electronegative atom and another electronegative atom in a different molecule or region of the same molecule. For example, between two water molecules. Peptide bonds (Choice B) are covenant bonds that hold amino acids together in polypeptide chains, and phosphodiester bonds (Choice D) are covalent bonds between the ribose sugars and phosphate groups, forming the backbone of DNA and RNA. Choices A, B and D are incorrect.

Explanation:
Photosynthesis (Choice B) is the process by which carbon dioxide in the air is converted to carbon compounds in green plants.

Respiration releases carbon dioxide (Choice A), and decomposition by decomposers (Choice C) also releases carbon dioxide. Transpiration is the process by which water is drawn up the stem of a plant to the leaves where it evaporates (Choice D) and is not involved directly in the carbon cycle.

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:
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:

During Prophase, chromosomes supercoil and become visible (Choice A). In Metaphase, chromosomes line up at the equator of the cell (Choices B and C). In Anaphase, sister chromatids are pulled apart (Choice D).

Explanation:
Choice B is not true. Not all genes are expressed in each cell. Only the necessary genes are expressed based on the specialised function of the cell. All other statements are true.