Correct Answer: A

Rationale: Aerobic respiration is the process by which cells use oxygen to convert glucose into energy. This process occurs in the mitochondria of cells and is the most efficient way to produce energy during exercise. Anaerobic respiration and glycolysis are alternative pathways for energy production when oxygen is limited, typically occurring during high-intensity exercise. Lactic acid fermentation, on the other hand, occurs in the absence of oxygen and leads to the production of lactic acid, causing muscle fatigue and soreness.

Correct Answer: A

Rationale: The correct answer is 'Solid.' Solids have a definite shape and volume, providing them with a strong resistance to changes in shape or size. Liquids and gases do not have a definite shape, making them prone to changing shape or size easily. Plasmas, on the other hand, are ionized gases with high energy levels and lack a definite shape or volume, which does not contribute to resistance against changes in shape or size. Therefore, the properties of solids make them best suited for resisting changes in shape or size compared to liquids, gases, and plasmas.

Correct Answer: B

Rationale: In meiosis I, sister chromatids are exact copies of each other, containing identical DNA sequences. On the other hand, homologous chromosomes are pairs of chromosomes, with one inherited from each parent, and they can have different versions of genes due to genetic recombination during crossing over in prophase I. Choice A is incorrect because homologous chromosomes naturally have different centromeres. Choice C is incorrect as sister chromatids and homologous chromosomes do not exhibit repulsion or attraction during synapsis. Choice D is incorrect as sister chromatids separate during anaphase II, not anaphase I, while homologous chromosomes separate during anaphase I.

Correct Answer: B

Rationale: Serotonin is a neurotransmitter that is associated with regulating mood, sleep, and memory. It plays a crucial role in maintaining emotional balance and is often a target in treating mood disorders like depression and anxiety. Serotonin also helps regulate sleep patterns and is connected to memory function. Dopamine (choice A) is more commonly linked to reward, motivation, and movement. Acetylcholine (choice C) is involved in muscle control and memory. Glutamate (choice D) is a major excitatory neurotransmitter in the brain but is not primarily associated with mood, sleep, and memory.

Correct Answer: D

Rationale: - Homozygous recessive genotype refers to an individual having two identical recessive alleles for a particular gene (e.g., rr for a trait where r represents the recessive allele). - Homozygous dominant genotype refers to an individual having two identical dominant alleles for a particular gene (e.g., RR for a trait where R represents the dominant allele). - The difference between the two genotypes lies in the specific alleles present in each case, with homozygous recessive having two recessive alleles and homozygous dominant having two dominant alleles. - This genetic difference results in different phenotypes being expressed, as the dominant allele typically masks the expression of the recessive allele in heterozygous individuals.