Nokea
What structure in a plant cell is surrounded by a double membrane and contains most of the genetic information used to control the cell?
- A. Mitochondrion
- B. Nucleus.
- C. Chromatin.
- D. Chromosome.
Correct Answer: B
Rationale: Rationale: The correct answer is B: Nucleus. The nucleus is surrounded by a double membrane and contains most of the genetic information in the form of DNA, which controls the cell's activities. Mitochondria (A) are involved in energy production, chromatin (C) is a complex of DNA and proteins within the nucleus, and chromosomes (D) are condensed structures of DNA found in the nucleus during cell division. Therefore, the nucleus is the structure that fits the description provided in the question.
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Why is homeostasis necessary?
- A. It maintains temperature.
- B. It maintains pH.
- C. It maintains glucose levels.
- D. All of the above.
Correct Answer: D
Rationale: Homeostasis is essential for maintaining the internal balance and stability of the body. It regulates various factors, such as temperature, pH levels, and glucose levels, to ensure optimal physiological function. Therefore, all the choices (temperature, pH, and glucose levels) are correct as they are all essential components of homeostasis, working together to keep the body's internal environment stable and functioning properly.
Which hormone is produced by the pineal gland?
- A. insulin
- B. testosterone
- C. melatonin
- D. epinephrine
Correct Answer: C
Rationale: The correct answer is melatonin (Choice C). The pineal gland is responsible for producing melatonin, a hormone that regulates sleep-wake cycles. Insulin (Choice A) is produced by the pancreas and regulates blood sugar levels. Testosterone (Choice B) is primarily produced by the testes in males and in smaller amounts by the ovaries in females. Epinephrine (Choice D) is produced by the adrenal glands and is involved in the body's fight-or-flight response.
What type of tissue is fat composed of?
- A. Connective
- B. Muscle
- C. Nervous
- D. Epithelial
Correct Answer: A
Rationale: The correct answer is A: Connective tissue. Fat tissue, also known as adipose tissue, is a type of connective tissue that stores energy in the form of fat. It provides insulation and serves as a reserve of energy. Muscle tissue (choice B) is responsible for movement, nervous tissue (choice C) transmits electrical signals throughout the body, and epithelial tissue (choice D) covers and protects body surfaces.
Anaerobic respiration happens in.............because..............
- A. Animals; they primarily rely on aerobic respiration
- B. Plants; they can perform photosynthesis
- C. Bacteria; they live in environments with low oxygen levels
- D. None of the above
Correct Answer: C
Rationale: Anaerobic respiration occurs in bacteria because they live in environments with low oxygen levels. In the absence of oxygen, these organisms utilize anaerobic respiration to generate energy. Animals and plants primarily rely on aerobic respiration, which requires oxygen to produce energy efficiently. Plants do not lack sunlight; they can perform photosynthesis to derive energy. Animals do require energy but predominantly use aerobic respiration when oxygen is available.
What is a characteristic of epithelial cells?
- A. Polarized
- B. Neutral
- C. Larger than other cells
- D. None of the above
Correct Answer: A
Rationale: Epithelial cells are polarized, meaning they have distinct apical and basal surfaces with different functions. This polarity is important for their specialized roles in absorption, secretion, and protection. Therefore, the correct answer is A: 'Polarized.' Choices B and C are incorrect as epithelial cells are not neutral and are not necessarily larger than other cells. Choice D is incorrect as epithelial cells do have specific characteristics.