Nokea
What is a gene, and what is the relationship between genes, genotype, and phenotype?
- A. A gene is a sequence of amino acids; genes make up proteins; genotype determines phenotype
- B. A gene is a portion of DNA; genes determine traits; genotype is the genetic makeup; phenotype is the physical manifestation
- C. A gene is a protein; proteins determine traits; genotype is the set of all genes
- D. A gene is a lipid; lipids determine traits; phenotype is the physical manifestation
Correct Answer: B
Rationale: A gene is a portion of DNA that contains the instructions for a specific trait. Genotype refers to the genetic makeup of an organism, encompassing all its genes. Phenotype, on the other hand, is the observable physical manifestation resulting from the interaction between an organism's genotype and environmental factors. Choice A is incorrect because genes do not consist of amino acids directly; they are sequences of nucleotides. Choice C is incorrect as genes do not determine traits directly but provide the instructions for proteins that may influence traits. Choice D is incorrect as genes are not lipids, and lipids do not determine traits; they are a type of biomolecule with different functions.
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How does the Law of Conservation of Mass apply to this reaction: 2H₂ + O₂ → 2H₂O?
- A. Electrons are not lost.
- B. The hydrogen does not lose mass.
- C. New water molecules are formed.
- D. There is no decrease or increase in matter.
Correct Answer: D
Rationale: The Law of Conservation of Mass states that matter cannot be created or destroyed in a chemical reaction. In the given reaction, 2 moles of hydrogen combine with 1 mole of oxygen to form 2 moles of water. The total mass of the reactants (hydrogen and oxygen) is equal to the total mass of the products (water), meaning there is no decrease or increase in matter. The total mass of the system remains constant, demonstrating the conservation of mass. Choices A, B, and C are incorrect because the conservation of mass does not specifically relate to electrons, individual elements (like hydrogen), or the formation of new molecules; instead, it focuses on the overall mass of the system before and after the reaction.
Using anatomical terms, what is the relationship of the sternum to the deltoid?
- A. Medial
- B. Lateral
- C. Superficial
- D. Posterior
Correct Answer: A
Rationale: The sternum is located at the midline of the body, closer to the center, making it medial to the deltoid. The deltoid muscle is positioned on the lateral side of the upper arm, away from the midline. Therefore, the correct relationship of the sternum to the deltoid is medial. 'Lateral' is incorrect as it refers to a position farther away from the midline, 'Superficial' is incorrect as it relates to a structure being closer to the surface, and 'Posterior' is incorrect as it indicates a position behind or toward the back.
Which muscle has involuntary cells that are branched and striated and connected by intercalated discs with gap junctions?
- A. Smooth muscle
- B. Cardiac muscle
- C. Skeletal muscle
- D. Epithelial muscle
Correct Answer: B
Rationale: The correct answer is B: Cardiac muscle. Cardiac muscle cells fit the description provided in the question; they are involuntary, striated, and branched, with intercalated discs containing gap junctions that allow for synchronized contractions of the heart. Smooth muscle (choice A) lacks striations and is found in the walls of internal organs. Skeletal muscle (choice C) is voluntary and attaches to bones for movement. 'Epithelial muscle' (choice D) is not a valid muscle type, making it an incorrect choice.
Which of the following is unique to covalent bonds?
- A. Most covalent bonds are formed between the elements H, F, N, and O.
- B. Covalent bonds are dependent on forming dipoles.
- C. Bonding electrons are shared between two or more atoms.
- D. Molecules with covalent bonds tend to have a crystalline solid structure.
Correct Answer: C
Rationale: The correct answer is C: 'Bonding electrons are shared between two or more atoms.' This statement is unique to covalent bonds. In covalent bonds, atoms share electrons to achieve a stable electron configuration, which leads to the formation of a bond. This sharing of electrons is a fundamental characteristic of covalent bonds and distinguishes them from other types of chemical bonds, such as ionic bonds, where electrons are transferred rather than shared. Choices A, B, and D do not represent unique characteristics of covalent bonds. Choice A describes some common elements involved in covalent bonds, choice B refers to the concept of dipoles, which can also exist in other types of bonds, and choice D describes a property of molecules (crystalline solid structure) that is not exclusive to covalent bonds.
What is the dermis composed of?
- A. Adipose tissue
- B. Epithelial cells
- C. Connective tissue
- D. Muscle tissue
Correct Answer: C
Rationale: The correct answer is C: Connective tissue. The dermis is primarily composed of connective tissue, which includes collagen and elastin fibers that provide strength and elasticity to the skin. It houses blood vessels, nerve endings, hair follicles, and glands, playing a crucial role in supporting the skin structure and function. Adipose tissue (choice A) is found in the subcutaneous layer beneath the dermis, providing insulation and energy storage. Epithelial cells (choice B) form the outermost layer of the skin called the epidermis. Muscle tissue (choice D) is not a significant component of the dermis but is found deeper in the body associated with movement and support.