stretch marks occur when

ATI TEAS 7

TEAS 7 science quizlet

1. What causes stretch marks?

A. The epidermis layer becomes inflamed
B. The dermis layer becomes inflamed
C. The dermis layer tears due to rapid stretching
D. Sebaceous glands become clogged

Correct answer: C

Rationale: Stretch marks occur when the dermis layer tears due to rapid stretching of the skin. This tearing leads to the appearance of stretch marks, which are often red or purple at first and then fade to a silvery-white color over time. Inflammation of the dermis or clogging of sebaceous glands are not directly related to the formation of stretch marks. Therefore, choices A, B, and D are incorrect as they do not describe the actual cause of stretch marks.

2. T cells in the immune system can be categorized into different types. What type of T cell directly kills infected body cells?

A. Helper T cells
B. Cytotoxic T cells
C. Regulatory T cells
D. Memory T cells

Correct answer: B

Rationale: Cytotoxic T cells directly kill infected body cells by recognizing specific antigens on the surface of infected cells and releasing cytotoxic substances to induce cell death, eliminating the infected cells. Helper T cells assist in coordinating the immune response, regulatory T cells help maintain immune tolerance, and memory T cells mount a faster and stronger response upon re-exposure to a previously encountered antigen. Therefore, the correct answer is cytotoxic T cells as they play a crucial role in directly targeting and destroying infected cells.

3. In nuclear fusion, where does the released energy originate from?

A. The fission of heavy nuclei
B. The binding energy released during the fusion of light nuclei
C. Electronic transitions within atoms
D. Matter-antimatter annihilation

Correct answer: B

Rationale: The correct answer is B: 'The binding energy released during the fusion of light nuclei.' Nuclear fusion involves the combination of light nuclei to form a heavier nucleus, releasing energy in the process. This energy arises from the binding energy that keeps the nucleus intact. As lighter nuclei fuse, they create a more stable nucleus, and the excess energy is emitted as radiation. This fundamental process is the primary source of energy in stars and holds promise as a potential future energy source on Earth. Choices A, C, and D are incorrect. Choice A, 'The fission of heavy nuclei,' is related to nuclear fission, not fusion. Choice C, 'Electronic transitions within atoms,' refers to energy release in atomic transitions, not nuclear fusion. Choice D, 'Matter-antimatter annihilation,' is a process where matter and antimatter collide, converting their mass into energy, but it is not the energy source for nuclear fusion.

4. Which term refers to a molecule of DNA and structural protein?

A. Lysosome
B. Centrosome
C. Chromosome
D. Genome

Correct answer: C

Rationale: The correct answer is C: Chromosome. A chromosome is a structure composed of DNA and proteins that carries genetic information. It is the condensed form of DNA associated with structural proteins, not just a molecule of DNA or protein. Lysosomes are membrane-bound organelles containing digestive enzymes, not DNA and protein. Centrosomes are involved in cell division, not related to DNA and protein together. A genome refers to an organism's complete set of DNA, not specifically a molecule containing both DNA and structural protein.

5. What is the Golgi apparatus?

A. A network of tubules that transport proteins and lipids throughout the cell
B. A sac-like structure that stores water and nutrients
C. The site of protein synthesis
D. The site of protein modification and packaging

Correct answer: D

Rationale: The Golgi apparatus is an organelle in the cell responsible for modifying, sorting, and packaging proteins and lipids for transport to their final destinations. It consists of a series of flattened sacs called cisternae and plays a crucial role in processing proteins synthesized in the endoplasmic reticulum. Option A is incorrect because the network of tubules that transport proteins and lipids throughout the cell is typically associated with the endoplasmic reticulum. Option B is incorrect as the structure described is more characteristic of a vacuole, which stores water and nutrients. Option C is incorrect as protein synthesis primarily occurs in the ribosomes, not the Golgi apparatus.