Nokea
Which of the following organelles is the site of cellular respiration?
- A. Nucleus
- B. Mitochondria
- C. Lysosomes
- D. Ribosomes
Correct Answer: B
Rationale: The correct answer is B: Mitochondria. Mitochondria are known as the powerhouse of the cell because they generate most of the cell's supply of ATP through cellular respiration. The other organelles listed, such as the nucleus (choice A), lysosomes (choice C), and ribosomes (choice D), do not play a direct role in cellular respiration. The nucleus contains genetic material, lysosomes are involved in digestion and waste removal, and ribosomes are responsible for protein synthesis.
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What is the composition of the cellular membrane?
- A. A bilayer of phospholipid molecules
- B. A single layer of phospholipid molecules
- C. Proteins that act as transport highways
- D. Carbohydrates
Correct Answer: A
Rationale: The cellular membrane is primarily composed of a phospholipid bilayer, which consists of two layers of phospholipid molecules. These molecules have a hydrophilic (water-attracting) head and hydrophobic (water-repelling) tail, creating a barrier that separates the internal cellular environment from the external surroundings. While proteins are embedded within this bilayer and act as transport channels, receptors, and structural support, carbohydrates are found on the outer surface of the membrane for cell recognition and signaling purposes. Therefore, the correct answer is a bilayer of phospholipid molecules.
Which of the following makes it possible to predict the genotype and phenotype of the offspring of sexual reproduction?
- A. Punnett square
- B. Chi-square
- C. Microscope
- D. None of these
Correct Answer: A
Rationale: The correct answer is A, Punnett square. A Punnett square is a tool specifically designed to predict the genotype and phenotype combinations of offspring resulting from a particular cross or breeding experiment. It helps in understanding the probability of different genotypes and phenotypes appearing in the offspring. Choice B, Chi-square, is a statistical test used to determine if there is a significant difference between the expected frequencies and the observed frequencies in a study. Choice C, Microscope, is used for viewing tiny structures and organisms, not for predicting genetic outcomes. Choice D, None of these, is incorrect as Punnett square is a valid tool for predicting genetic outcomes in offspring.
What is the main objective of the translation stage of protein synthesis?
- A. To produce amino acids
- B. To produce nucleotides
- C. To produce fatty acids
- D. To produce proteins
Correct Answer: D
Rationale: The main objective of the translation stage of protein synthesis is to produce proteins. During translation, ribosomes decode mRNA sequences to synthesize proteins by linking amino acids together. Choice A, 'To produce amino acids,' is incorrect as amino acids are the building blocks of proteins and are not produced during translation. Choices B and C, 'To produce nucleotides' and 'To produce fatty acids,' are also incorrect as these molecules are not the direct products of the translation stage of protein synthesis.
Which of the following terms is used to represent two alleles that are the same type?
- A. Homosynchronous
- B. Hypersynchronous
- C. Heterozygous
- D. Homozygous
Correct Answer: D
Rationale: The correct answer is D, 'Homozygous.' Homozygous refers to having two identical alleles for a particular gene. In this context, 'Homosynchronous' (choice A) is not a recognized genetic term. 'Hypersynchronous' (choice B) is not a term used in genetics. 'Heterozygous' (choice C) refers to having two different alleles for a particular gene, which is the opposite of homozygous.
Which of the following is the term used to represent alternative versions of a gene?
- A. Alleles
- B. Binary fission
- C. Heterozygous
- D. Homozygous
Correct Answer: A
Rationale: The correct answer is A: Alleles. Alleles are different versions of a gene that can exist at a specific locus on a chromosome. This term specifically refers to the different forms of a gene that can exist. Choices B, C, and D are incorrect because they do not represent alternative versions of a gene. Binary fission is a form of asexual reproduction in single-celled organisms, while heterozygous and homozygous refer to the genetic makeup of an individual rather than alternative versions of a gene.