Explanation​:
Water is cohesive because it is a polar molecule. The oxygen atom in one water molecule forms a hydrogen bond with the hydrogen atom of another water molecule. In xylem vessels water is attracted to the hydrophilic regions of the cell wall and hydrogen bonds are formed. This an accurate description of the adhesive properties of water in the context of water transport in plants (Choice A). These statements are reversed in Choice D.

Ions dissolve in water, but this is not related to the cohesive (Choice B) or adhesive (Choice C) properties of water.

Explanation​:
Choice B is correct because Rubisco is the name of the enzyme which is responsible for the fixation of carbon during photosynthesis. Choice A is incorrect as rhodopsin is a pigment found in the retina which is responsible for detecting light . Choices C and D are incorrect as neither are enzymes, with collagen being a structural component of tissues such as skin and insulin being a hormone responsible for regulating blood glucose levels.

Explanation:
Choice C is correct because ribosomes are organelles found on the surface of the rough endoplasmic reticulum and are needed to synthesise polypeptide chains.

The nucleus (Choice A) contains DNA, some of which codes for the polypeptides made by the ribosomes. The role of vesicles (Choice B) is to store substances and to transport substances, including proteins, between cellular compartments. The mitochondria (Choice D) are the organelles responsible for aerobic respiration.

Explanation​:
Choice C is correct because cellular components are separated using cell fractionation, which requires the ultracentrifuge to separate the cellular components based on density.

Choice A is incorrect because chromatography separates mixtures of solutes, such as pigments, based on adhesion. Choice B is incorrect because gel electrophoresis separates molecules such as nucleic acids based on size, charge or both. Choice D is incorrect because PCR is used to amplify DNA fragments and is not a separation technique.

Explanation:
Centrifugation is a technique that primarily separates substances based on their density. When a mixture is centrifuged, particles or components with higher density sediment to the bottom of the tube. Choice A is, therefore, correct.

Centrifugation does not separate substances based on their charge. Electrophoresis is a technique that separates particles or molecules based on their charge. Choice B is, therefore, incorrect. Centrifugation does not directly separate substances based on their chemical composition. Other techniques like chromatography may be more suitable for separating substances by chemical composition. Choice C is, therefore, incorrect. Centrifugation does not separate substances based on their colour. Colour differences might be observed during centrifugation, but they are not the basis for separation. Choice D is, therefore, incorrect.

Explanation​:
Water diffuses out of stomata from the inner air space of leaves during transpiration (Option I). Because oxygen is produced during photosynthesis, its concentration is generally higher in the inner air space than the atmosphere which means it diffuses out through the stomata (Option II). Mineral ions (Option III) enter plants through root cells, not through the stomata.

Explanation​:
In prokaryotes, the mRNA produced after transcription is ready for translation and does not undergo splicing. In contrast, eukaryotic pre-mRNA undergoes splicing to remove introns and join exons, producing mature mRNA. Choice C is, therefore, correct.

Both prokaryotes and eukaryotes use DNA as a template for transcription. Choice A is, therefore, incorrect. In prokaryotes, transcription occurs in the cytoplasm, while in eukaryotes, it occurs in the nucleus. Choice B is, therefore, incorrect. Splicing of mRNA occurs in eukaryotes, not prokaryotes. Choice D is, therefore, incorrect

Explanation​:
Choice A - There are still stem cells that can be found in the adult body. For example, stem cells are present in the bone marrow, skin, and liver.

Choice B - The foetal stage of development happens from the ninth week after conception until birth. In this stage, the organs have begun to form, and these developing organs come from differentiated stem cells.

Choice C - Stem cells are characterised by their capacity to divide and differentiate. These cells are similar to a blank canvas with the possibility of becoming any type of cell.

Choice D - Stem cells are yet to undergo specialisation through the process of differentiation.

Explanation​:
Choice D is correct because multipotent stem cells can produce only cells of a particular tissue or organ. Choice A is incorrect because pluripotent stem cells are usually found in early embryos and are capable of differentiating to become any cell type found in the organism except for extra-embryonic tissues such as the placenta. Additionally, they are not found in bone marrow. Choice B is incorrect because totipotent stem cells are only found in early stages of embryonic development and can produce all cell types of the organism as well as extra-embryonic tissues such as the placenta. Choice C is incorrect because stem cells are by definition, undifferentiated.

Explanation​:
Obligate anaerobes are single-celled organisms that will not survive if oxygen is present. Facultative anaerobes are organisms that can either respire aerobically or anaerobically. Obligate aerobes can only respire if oxygen is present and cannot survive in conditions low in oxygen. Therefore Choice A is correct.

Choices B and D are incorrect because obligate anaerobes cannot respire when oxygen is present. Choice C is incorrect as obligate anaerobes require anoxic conditions, and obligate aerobes cannot carry out anaerobic respiration.

Explanation​:
Sieve plates (Statement I) and plasmodesmata (Statement II) are features found in phloem. Sieve plates possess pores which allow continual flow of sap through the sieve tubes. Plasmodesmata are small channels which connect the sieve tube elements to the adjacent companion cells. A high lignin content (Statement III) is found in xylem vessels. It provides support to withstand hydrostatic pressure, and is also impermeable to water.

Explanation​:
Statement II is incorrect as both starch and glycogen are made up of $\alpha -$ glucose molecules (Choices B and D). Choice A is incorrect as it only includes one correct statement (statement I).

Explanation:
Regular exercise prevents the buildup of fatty plaque in the coronary arteries thereby preventing heart disease (Choice D). Some of the factors that cause the buildup of fatty plaque and occlusion of the arteries causing chest pain are high blood pressure (Choice A), high blood sugar due to diabetes (Choice B) and some genetic factors (Choice C).

Explanation​:
The process of air entering the lungs is known as inhalation. The term $\text{“}$inspiration$\text{”}$ is used instead of inhalation sometimes. In order for inhalation to take place, the pressure inside the lungs must be lower compared to atmospheric pressure. To decrease the pressure inside the lungs, the external intercostal muscles must contract and become shorter to pull the ribs up and out, increasing the volume inside the thorax.

Choice A is incorrect because abdominal wall muscles relax during inhalation. Lengthening of the abdominal muscles can contribute to inhalation by pushing the abdominal wall out which increases the volume inside the thorax.

Choice B is incorrect because when the diaphragm relaxes it forms a dome shape and therefore reduces the volume of the thorax. This occurs during exhalation.

Choice D is incorrect because internal intercostal muscles relax and lengthen during inhalation. They contract and shorten during exhalation.

Explanation​:
Choice D is correct because line transects can be used to show animal or plant distributions. Choices A, B and C are all factors that could be measured using different sensors that could provide meaning to plant or animal distributions.

Explanation​:
Choice C – The statement is false. Phospholipids are a class of lipids which have a hydrophilic “head” and two hydrophobic “tails.” The heads contain a phosphate group and the two tails each contain one fatty acid.

Choice A, B, and D – These statements are all true.

Explanation:
Holozoic nutrition refers to the type of nutrition where organisms ingest whole or partially whole food items (Statement II). The ingested food is then broken down by the organism's internal digestive system (Statement III). Therefore Choice B is correct. Saprotrophs (Statement I) are organisms that obtain their nutrients by decomposing dead and decaying organic matter externally and then absorbing the nutrients. Therefore Choices A, C and D are not correct as they all include Statement I.

Explanation​:
An ecosystem refers to an area where organisms interact with each other and with the physical environment.

A habitat (Choice A) refers to the environment in which a species normally lives. A population (Choice C) is a group of organisms of the same species living in the same area at the same time which can interbreed. A community (Choice D) is a group of populations living and interacting with each other in the same habitat.

Explanation​:
Ducks and fish are consumers (Choice B, C and D), which is a type of heterotroph, whereas Azolla and rice can carry out photosynthesis and are, therefore, autotrophs (self-feeding).

Explanation​:
Choice A - The surface area of a cell affects the rate of diffusion of materials in and out of the cell.

Choice B - A small cell will have a bigger surface area to volume ratio which means that diffusion will be easier and other cell processes will become faster.

Choice C - The volume of the cell affects the rate at which materials are produced.

Choice D - A larger spherical cell will have a low surface area to volume ratio. Therefore, the comparatively large volume of cytoplasm may produce waste products at a rate too high to rely on diffusion through the comparatively small surface area of the cell membrane.

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​:
Autotrophs are producers (Choice A) which synthesize their own organic compounds. Consumers gain their nutrition by feeding (Choice B) on other organisms. Detritivores consume dead organic matter (Choice C) by ingestion. Saprotrophs break down food outside their bodies (Choice D) by secreting enzymes and then ingesting the digested compounds.

Explanation​:
Amino acids (Choice B) can form polypeptides through the formation of peptide bonds as a result of condensation reactions. Fatty acids (Choice A) are involved in the formation of lipids and are not monomers. Proteins (Choice C) are composed of one or more polypeptides and are polymers. Nucleotides (Choice D) are the building blocks of DNA and RNA.

Explanation:
Choice A is correct because there is no compartmentalisation in prokaryotes, hence transcription and translation both take place in the cytoplasm.

Choice B is incorrect because mRNA splicing does not occur in prokaryotes, but does occur in the nucleus of eukaryotic cells. Choice C and D are incorrect because the regulation of transcription and translation of mRNA into a polypeptide chain occurs in both prokaryotes and eukaryotes.

Explanation:
Choice C is correct because the habitat is a place a community, population, species, or organism lives. Choice A refers to an organism's niche, Choice B refers to the ecosystem, and Choice D refers to a community.