the gram stain is a differential staining technique used to classify bacteria based on their cell wall composition gram positive bacteria appear
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ATI TEAS 7

TEAS 7 science practice

1. The Gram stain is a differential staining technique used to classify bacteria based on their cell wall composition. Gram-positive bacteria appear

Correct answer: D

Rationale: The Gram stain is a differential staining technique that categorizes bacteria into two groups based on their cell wall composition: Gram-positive and Gram-negative. Gram-positive bacteria have a thick layer of peptidoglycan in their cell walls, which retains the crystal violet stain used in the Gram staining procedure. Consequently, Gram-positive bacteria appear purple under the microscope after staining. On the other hand, Gram-negative bacteria possess a thinner peptidoglycan layer and an outer membrane that can be penetrated by the counterstain safranin, leading them to appear pink or red. Blue is not typically used to describe the color of bacteria in a Gram stain, making it an incorrect choice.

2. Which cellular organelle is used for digestion to recycle materials?

Correct answer: B

Rationale: The lysosome is the correct cellular organelle used for digestion to recycle materials. Lysosomes contain enzymes that break down waste materials, cellular debris, and ingested substances. This process helps in recycling nutrients and maintaining cellular homeostasis. The Golgi apparatus is involved in processing and packaging proteins, the centrioles play a role in cell division, and the mitochondria are responsible for energy production. However, none of these organelles are primarily used for digestion and recycling of materials within the cell.

3. Which of the following is NOT a typical component of healthy semen?

Correct answer: D

Rationale: Healthy semen is composed of sperm, fructose (sugar), and prostaglandins. Urine is not a typical component of semen. While semen is ejaculated during sexual activity, urine is expelled through a separate pathway in the male reproductive system. Therefore, the correct answer is 'Urine.' Choices A, B, and C are all components found in healthy semen.

4. What is the common name for the organic compound CH₃OH?

Correct answer: C

Rationale: The common name for the organic compound CH₃OH is methanol. Methane (A) has the chemical formula CH₄. Ethanol (B) corresponds to the formula C₂H₅OH. Butanol (D) is a compound with the formula C₄H₉OH. The correct answer is C - Methanol, which is the common name for CH₃OH, while the other options correspond to different organic compounds with distinct formulas. Therefore, methanol is the correct choice when identifying the common name for the compound CH₃OH.

5. What is the role of the hypothalamus in the body?

Correct answer: B

Rationale: The correct answer is B: 'To regulate hormones.' The hypothalamus plays a crucial role in regulating hormones and maintaining homeostasis by controlling various functions such as hunger, thirst, body temperature, and sleep-wake cycles. While digestion, body temperature, and the immune system are important bodily functions, they are not primarily controlled by the hypothalamus. Therefore, choices A, C, and D are incorrect as they do not accurately represent the primary function of the hypothalamus.

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