What is the smallest unit that can encode for a trait?

Correct Answer: B

Rationale: The correct answer is B - a gene. Genes are the smallest units that can encode for a trait as they contain the specific instructions for producing a particular characteristic or protein. While codons are sequences of nucleotides that code for specific amino acids in a protein, they are not the smallest unit that encodes for a trait. Nucleotides are the building blocks of DNA and RNA, and chromosomes are made up of DNA and proteins, containing many genes.

Correct Answer: D

Rationale: The correct answer is D: T cells are a specialized type of white blood cell that play a crucial role in the immune response. They are produced in the bone marrow and mature in the thymus gland. T cells help coordinate and regulate the immune response to pathogens and foreign substances by interacting with other immune cells. Choices A, B, and C are incorrect. T cells are not exclusively seen in individuals with leukemia; they are a normal component of the immune system found in healthy individuals. While it is true that T cells are a specialized type of white blood cell, the key characteristic being tested in this question is their role in the immune response. Lastly, T cells do mature in the thymus, but this alone does not encompass the full scope of their function in the immune system.

Correct Answer: A

Rationale: The correct answer is A: Phenotype. Phenotype specifically refers to the observable physical characteristics resulting from the interaction of an individual's genetic makeup (genotype) with environmental influences. It represents the outward expression of an organism's genetic makeup. Allele, represented by choice B, refers to different forms of a gene and is not the visible expression of a trait. Gamete, represented by choice C, is a reproductive cell and not directly related to the physical expression of traits. Genotype, represented by choice D, refers to the genetic makeup of an organism and is distinct from the observable physical characteristics denoted by phenotype.

Correct Answer: D

Rationale: The correct answer is 'D: Ionic bond.' An ionic bond is formed when electrons are transferred between atoms. In an ionic bond, one atom donates electrons to another atom, resulting in the formation of positively and negatively charged ions that are attracted to each other, creating a strong bond. Choice A, 'Transfer bond,' is incorrect because there is no common term known as a 'Transfer bond' in chemistry. Choice B, 'Static bond,' is incorrect as it does not describe the process of electron transfer between atoms. Choice C, 'Covalent bond,' is incorrect because in a covalent bond, electrons are shared between atoms rather than transferred outright, making it different from an ionic bond.

Correct Answer: D

Rationale: The correct answer is D: Plasma cells. Plasma cells are a type of white blood cell that secretes antibodies. Antibodies are essential components of the immune system, as they help in identifying and neutralizing pathogens. Choice A, B, and C are incorrect as bacterial cells and viral cells do not secrete antibodies, and lymph cells are involved in the immune response but do not secrete antibodies like plasma cells.