how are lipids different than other organic molecules

HESI A2

HESI A2 Practice Test Biology

1. How are lipids different from other organic molecules?

A. They are indivisible.
B. They are not water soluble.
C. They contain zinc.
D. They form long proteins.

Correct answer: B

Rationale: The correct answer is B: 'They are not water soluble.' Lipids are not water-soluble, which distinguishes them from other organic molecules. Choice A is incorrect because lipids are not indivisible; they can be broken down into fatty acids and glycerol. Choice C is incorrect as lipids do not necessarily contain zinc; they are a diverse group of molecules. Choice D is incorrect because lipids do not form long proteins; proteins are made up of amino acids, not lipids.

2. What type of cells possess a cell membrane?

A. Prokaryotic cells only
B. Eukaryotic cells only
C. Both prokaryotic and eukaryotic cells
D. None of the above

Correct answer: C

Rationale: Cell membranes are present in both prokaryotic and eukaryotic cells. The cell membrane serves as a barrier that encloses the cell contents and regulates the entry and exit of substances in and out of the cell. It is a fundamental structure found in all types of cells, regardless of whether they are prokaryotic (lacking a nucleus) or eukaryotic (containing a nucleus). Choice A is incorrect because eukaryotic cells also possess cell membranes. Choice B is incorrect as prokaryotic cells, such as bacteria, also have cell membranes. Choice D is incorrect as both prokaryotic and eukaryotic cells have cell membranes.

3. How should a researcher test the hypothesis that a particular species of bird vocalizes most in the hours around dawn?

A. Observe a flock of the birds in captivity and record them at two-hour intervals from predawn until sunset for a month.
B. Observe a flock of the birds in the wild and record them at one-hour intervals from predawn until sunset in several seasons.
C. Observe a flock of the birds in the wild and record them in predawn and postdawn hours every day for six months.
D. Observe a flock of the birds in the wild, record them at one-hour intervals for a month, and compare that recording to recordings of other species.

Correct answer: C

Rationale: Observing a flock of the birds in the wild and recording them in predawn and postdawn hours every day for six months would be the best way to test the hypothesis that a particular species of bird vocalizes most in the hours around dawn. This method allows for consistent monitoring of the birds during specific times of interest over an extended period, providing a comprehensive dataset to accurately analyze the vocalization patterns. Options A and B do not focus specifically on dawn hours, making them less suitable for testing the hypothesis. Option D introduces a comparison with other species, which is unnecessary and distracts from the main objective of studying the vocalization pattern of the particular bird species around dawn.

4. The procedure to focus an image using a compound microscope involves

A. Adjusting the coarse adjustment each time a new magnification is selected
B. Adjusting the fine adjustment each time a new magnification is selected
C. Adjusting the stage each time a new magnification is selected
D. All of the above

Correct answer: B

Rationale: When using a compound microscope, it is essential to adjust the fine adjustment knob each time you switch to a new magnification level. The fine adjustment knob allows for precise focusing on the specimen at different magnifications, ensuring a clear and sharp image. The coarse adjustment knob is typically used only at the lower magnification settings to bring the image into view roughly. Adjusting the stage may be necessary based on the size and thickness of the specimen, but it does not need to be done every time a new magnification is selected. Therefore, option B is the correct choice as it focuses on the key aspect of precise focusing during magnification changes.

5. What is the classification of organisms into different categories based on their physical characteristics and presumed natural relationship?

A. Biology
B. Taxonomy
C. Grouping
D. Nomenclature

Correct answer: B

Rationale: Taxonomy is the correct answer. Taxonomy is the branch of biology that deals with the classification of organisms into different categories based on their physical characteristics and presumed natural relationship. It involves naming and categorizing organisms into hierarchical groups to show their evolutionary relationships. Choice A, 'Biology,' is incorrect as it is the broader field of science that encompasses the study of living organisms. Choice C, 'Grouping,' is incorrect as it is a general term that does not specifically refer to the systematic classification of organisms. Choice D, 'Nomenclature,' is incorrect as it refers to the system of naming organisms rather than the classification based on physical characteristics and natural relationships.