Which of the following is NOT a source of genetic variation in a population?

Correct Answer: D

Rationale: Rationale: A) Mutations in genes: Mutations are changes in the DNA sequence that can introduce new alleles into a population, leading to genetic variation. B) Genetic drift (random fluctuations in allele frequencies): Genetic drift refers to random changes in allele frequencies in a population, which can lead to genetic variation through chance events. C) Gene flow (movement of genes between populations): Gene flow occurs when individuals move between populations, bringing new alleles with them and increasing genetic variation within populations. D) Blending inheritance (traits of parents are averaged in offspring): Blending inheritance was a historical theory that suggested offspring inherit a blend of traits from their parents, leading to a reduction in genetic variation over time. However, this concept has been disproven by the understanding of Mendelian genetics, where traits are inherited independently and do not blend together. Therefore, blending inheritance does not contribute

Correct Answer: C

Rationale: The correct answer is the Lymphatic system (option C). The lymphatic system is responsible for draining excess fluid and waste products from tissues. It works alongside the circulatory system to maintain fluid balance in the body. The circulatory system (option A) transports blood, the digestive system (option B) processes food, absorbs nutrients, and eliminates solid waste, while the respiratory system (option D) is responsible for gas exchange, specifically the intake of oxygen and removal of carbon dioxide.

Correct Answer: A

Rationale: The correct answer is the cell wall, as it is the rigid structure that provides shape and support to plant cells. The cell wall is located outside the plasma membrane and is primarily composed of cellulose, giving it its rigid nature. The plasma membrane (option B) is a semi-permeable membrane surrounding the cell that regulates the movement of substances in and out of the cell. The nucleus (option C) houses the cell's genetic material and controls cellular activities. Cytoplasm (option D) is the gel-like substance within the cell that surrounds organelles and where various cellular processes take place, but it does not provide the rigid structure and support that the cell wall does.

Correct Answer: A

Rationale: Microfilaments are thin, solid rods made of the protein actin and are primarily responsible for providing structural support to the cell and determining its shape. While they also play a role in cell movement, their main function is related to maintaining the structural integrity of the cell. Choice B, 'Facilitate cell movement and contraction,' describes microtubules, which are responsible for facilitating cell movement, providing structural support, and aiding in cell division. Choice C, 'Form the mitotic spindle during cell division,' specifically refers to the function of microtubules in forming the mitotic spindle. Choice D, 'Transport materials within the cell,' is characteristic of microtubules that are involved in intracellular transport of organelles and materials within the cell.

Correct Answer: C

Rationale: The primary function of nervous tissue is communication and coordination within the body. Nervous tissue is composed of neurons that transmit electrical signals and supporting cells known as neuroglia. Movement is primarily controlled by the muscular system, protection is mainly provided by the skeletal system and immune system, and nutrient transport is carried out by the circulatory system. Therefore, choices A, B, and D are incorrect as they do not align with the primary function of nervous tissue.