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 is the role of tRNA during protein synthesis?

A. Carries amino acids to the ribosome
B. Links nucleotides together
C. Copies DNA sequences
D. Replicates genetic material

Correct answer: A

Rationale: During protein synthesis, tRNA plays the crucial role of carrying amino acids to the ribosome. This process ensures that the correct amino acids are brought to the ribosome according to the mRNA sequence. Choice B, linking nucleotides together, refers to the role of RNA polymerase in transcription, not tRNA. Choice C, copying DNA sequences, is the function of DNA polymerase during DNA replication, while choice D, replicating genetic material, is an overarching function of DNA replication, not specific to tRNA's role in protein synthesis.

3. Within the biological hierarchical system of organization, which of the following is least inclusive?

A. phylum
B. order
C. kingdom
D. species

Correct answer: D

Rationale: The correct answer is 'D: species.' In the biological hierarchical system of organization, a species is the least inclusive level. A species consists of organisms that share similar characteristics and can interbreed to produce fertile offspring. On the other hand, a phylum, order, and kingdom are more inclusive classifications that encompass multiple species. Phylum groups together related classes, order groups together related families, and kingdom groups together related phyla. Therefore, species is the least inclusive category within the biological hierarchical system.

4. Which gives the order of four taxonomic categories from least to most specific?

A. Kingdom, phylum, class, order
B. Kingdom, phylum, order, class
C. Kingdom, order, phylum, class
D. Kingdom, class, order, phylum

Correct answer: A

Rationale: The correct order of the four taxonomic categories from least to most specific is Kingdom, phylum, class, and order. This sequence adheres to the hierarchical system of classification where organisms are grouped based on shared characteristics, becoming more specific as you move from Kingdom to order. Choice B is incorrect as the order of 'order' and 'class' is swapped. Choice C is incorrect as 'order' precedes 'phylum' instead of following it. Choice D is incorrect as 'class' should come before 'order'.

5. 72 chromosomes undergo meiosis. How many chromosomes will be in each gamete?

A. 18
B. 36
C. 72
D. 144

Correct answer: A

Rationale: During meiosis, the number of chromosomes is halved in each gamete. Since 72 chromosomes undergo meiosis, each gamete will contain half of that number, which is 36 chromosomes. Therefore, the correct answer is 18 chromosomes in each gamete. Choice B (36 chromosomes) is incorrect because it represents the total number of chromosomes that undergo meiosis, not the number in each gamete. Choice C (72 chromosomes) is incorrect as it represents the initial number of chromosomes, not the number in each gamete after meiosis. Choice D (144 chromosomes) is incorrect as it doubles the initial number of chromosomes, which is not the outcome of meiosis.