Nokea
If a mother's ______ cell contains mutated DNA, this mutation can be passed to her offspring.
- A. germ
- B. white blood
- C. stem
- D. somatic
Correct Answer: A
Rationale: The correct answer is A: 'germ.' Germ cells, which include egg and sperm cells, are responsible for passing genetic information to offspring. Mutations in these cells can be inherited by the next generation. In contrast, mutations in somatic cells (D), like skin or muscle cells, are not passed on to offspring as they are not involved in reproduction. White blood cells (B) and stem cells (C) are not directly involved in transmitting genetic mutations to offspring.
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In a specific scenario, red flowers are dominant over white flowers. A plant heterozygous for red flowers and a plant with white flowers are crossed. What is the expected proportion of phenotypes in the next generation?
- A. 2 red, 2 white
- B. 3 red, 1 white
- C. 4 red, 0 white
- D. 1 red, 3 white
Correct Answer: A
Rationale: When a plant heterozygous for red flowers (Rr) is crossed with a plant having white flowers (rr), according to Mendelian genetics, the Punnett square predicts a 1:1 ratio of red (Rr) to white (rr) flowers in the offspring. This means that the expected proportion in the next generation would be 2 red flowers and 2 white flowers.
If A represents atomic mass and Z represents atomic number, which of the following describes an atom after a proton is emitted from its nucleus?
- A. A+1, Z-1
- B. A-1, Z+1
- C. A+1, Z+1
- D. A-1, Z-1
Correct Answer: D
Rationale: When a proton is emitted from the nucleus of an atom, the atomic mass (A) remains the same while the atomic number (Z) decreases by 1. This is because a proton carries a positive charge and has a mass of 1 atomic mass unit. Therefore, the correct description after the emission of a proton is A-1, Z-1. The atomic mass decreases by 1 because a proton is lost, and the atomic number decreases by 1 since the nucleus loses a positively charged particle.
Which of the following is an example of a biological macromolecule?
- A. Monosaccharide
- B. Protein
- C. Nucleic acid
- D. Amino acid
Correct Answer: B
Rationale: The correct answer is B, 'Protein.' Proteins are biological macromolecules composed of amino acid chains. They play vital roles in cellular functions, including catalyzing reactions, providing structural support, and acting as signaling molecules. Monosaccharides are simple sugars, nucleic acids are genetic materials such as DNA and RNA, and amino acids are the fundamental units that make up proteins.
Which of the following events occurs in metaphase I of meiosis and contributes to genetic variation?
- A. Independent assortment
- B. Reduction division
- C. Crossing over
- D. Homologous pairing
Correct Answer: A
Rationale: Independent assortment is the correct answer as it occurs during metaphase I of meiosis. This process leads to genetic variation by randomly aligning homologous chromosomes along the metaphase plate, creating diverse combinations of maternal and paternal chromosomes in the resulting daughter cells. Consequently, this random assortment increases genetic diversity among the gametes that are formed. During independent assortment, homologous chromosomes randomly align at the metaphase plate, leading to different combinations of chromosomes in the daughter cells. This shuffling of genetic material from maternal and paternal sources results in offspring with unique genetic makeups, contributing to genetic diversity within a population.
Which of the following processes uses an electrochemical gradient to produce ATP?
- A. Chemiosmosis
- B. Cell division
- C. Fermentation
- D. Photosynthesis
Correct Answer: A
Rationale: Chemiosmosis is the process where ATP is produced as protons flow down their electrochemical gradient across a membrane, typically during cellular respiration or photosynthesis. Cell division and fermentation do not produce ATP via an electrochemical gradient.