Nokea
Epithelial cells are:
- A. Polarized
- B. Neutral
- C. Larger than other cells
- D. None of the above
Correct Answer: A
Rationale: Epithelial cells have a distinct top (apical) and bottom (basal) side, demonstrating polarity. This polarity is essential for their specialized functions, such as secretion, absorption, and barrier formation. Choice B, 'Neutral,' is incorrect as epithelial cells exhibit polarity. Choice C, 'Larger than other cells,' is incorrect as epithelial cells come in various sizes and are not specifically larger than other cell types. Choice D, 'None of the above,' is incorrect as epithelial cells are indeed polarized.
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Prokaryotic cells:
- A. Have a nucleus
- B. Have a capsule
- C. Have membrane-bound organelles
- D. Cannot move on their own
Correct Answer: B
Rationale: Prokaryotic cells do not have a nucleus or membrane-bound organelles. One characteristic feature of prokaryotic cells is the presence of a capsule, which is a protective layer outside the cell wall. This capsule helps the prokaryotic cell adhere to surfaces, evade the host immune system, and protect against desiccation. Choice A is incorrect because prokaryotic cells lack a nucleus. Choice C is incorrect as prokaryotic cells do not have membrane-bound organelles. Choice D is incorrect as prokaryotic cells can move using structures like flagella or pili.
Select the option that best shows complementary base pairing in DNA:
- A. A and G
- B. A and C
- C. A and A
- D. A and T
Correct Answer: D
Rationale: The correct answer is D. A purine (A) must pair with a pyrimidine (T) in DNA. This eliminates options A and C as they do not follow the rule of complementary base pairing. Adenine (A) always pairs with thymine (T) due to their specific shape and bonding properties in DNA structure. Choice B is incorrect because adenine does not pair with cytosine in DNA.
Which of the following are components of the endocrine system?
- A. The pituitary gland
- B. The thyroid gland
- C. The adrenal glands
- D. All of the Above
Correct Answer: D
Rationale: The endocrine system comprises a network of glands that produce and release hormones to regulate bodily functions. The pituitary gland, thyroid gland, and adrenal glands are essential components of this system. The pituitary gland secretes various hormones that control other glands and some body functions. The thyroid gland regulates metabolism, growth, and energy levels by producing thyroid hormones. The adrenal glands produce hormones involved in stress response, metabolism, and immune function. Therefore, all of the above glands are integral parts of the endocrine system, making choice D the correct answer.
Why is it important for cells to undergo mitosis?
- A. mitosis allows for reproduction with male and female gametes
- B. mitosis increases variation within the species
- C. mitosis produces cells that are different from the parent cell
- D. mitosis produces cells for growth and repair of body tissue
Correct Answer: D
Rationale: It is important for cells to undergo mitosis because it produces cells for the growth and repair of body tissues. Mitosis allows for the formation of genetically identical daughter cells, ensuring proper function and maintenance of the organism's body. By producing new cells, mitosis helps in the replenishment of damaged or worn-out tissue and supports overall growth and development. Choices A, B, and C are incorrect because mitosis is not directly related to reproduction with male and female gametes, increasing variation within the species, or producing cells different from the parent cell. These functions are more associated with meiosis, which is specifically for sexual reproduction and genetic diversity.
Genes control heredity in man and other organisms. This gene is ___
- A. A segment of DNA
- B. A bead-like structure on the chromosomes
- C. A protein molecule
- D. A segment of RNA
Correct Answer: A
Rationale: Genes are sections of DNA that contain instructions for building and operating living organisms. These sections of DNA contain the genetic information that is passed on from one generation to the next. Genes are composed of specific sequences of nucleotides within the DNA molecule. Therefore, genes are best described as segments of DNA. Choice A is correct. Choice B is incorrect because genes are not bead-like structures on chromosomes but specific sequences of DNA. Choice C is incorrect because genes are not protein molecules but rather sequences of nucleotides. Choice D is incorrect because genes are not segments of RNA but DNA.