Nokea
What is the purpose of the mitochondria?
- A. Control the cell
- B. Generate energy
- C. Synthesize proteins
- D. Package waste for removal
Correct Answer: B
Rationale: The mitochondria's main function is to generate energy for the cell through the process of cellular respiration. This organelle is often referred to as the powerhouse of the cell due to its role in producing adenosine triphosphate (ATP), the cell's main energy currency. While other organelles are responsible for activities like controlling the cell (nucleus) or synthesizing proteins (ribosomes), the mitochondria's primary role is energy production.
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During which phase is the chromosome number reduced from diploid to haploid?
- A. S phase
- B. interphase
- C. mitosis
- D. meiosis I
Correct Answer: D
Rationale: The correct answer is meiosis I. Meiosis is a specialized cell division process that occurs in sexually reproducing organisms to produce gametes (sperm and egg). In meiosis I, the chromosome number is reduced from diploid (2n) to haploid (n) by separating homologous chromosomes. This reduction in chromosome number is crucial for maintaining the correct chromosome count in sexually reproducing organisms and ensuring genetic diversity in offspring.
What type of bond holds molecules of water together with other water molecules?
- A. Ionic
- B. Covalent
- C. Hydrogen
- D. Molecular
Correct Answer: C
Rationale: The correct answer is 'C: Hydrogen.' Molecules of water are held together by hydrogen bonds. These bonds form between the hydrogen atom of one water molecule and the oxygen atom of another water molecule. Hydrogen bonds are weaker than covalent bonds but are crucial in various biological processes, such as maintaining the unique properties of water and facilitating specific interactions in biological molecules.
Why does cellular respiration occur?
- A. Cells can copy DNA
- B. Cells can breathe
- C. Cells can convert nutrients to energy
- D. Cells can divide
Correct Answer: C
Rationale: Cellular respiration is the metabolic process in which cells convert nutrients, such as glucose, into energy in the form of ATP (adenosine triphosphate). This energy is crucial for the cell to perform its various functions and maintain life processes. Options A, B, and D do not accurately describe the purpose of cellular respiration, which is primarily about energy production to support cellular activities.
Which of the following is a protein?
- A. cellulose
- B. hemoglobin
- C. estrogen
- D. ATP
Correct Answer: B
Rationale: Hemoglobin is the correct answer as it is a protein. Proteins are large, complex molecules composed of amino acids that are essential for various structural and functional roles in the body. Hemoglobin, specifically, is a protein found in red blood cells and is responsible for carrying oxygen from the lungs to different parts of the body, highlighting its crucial role in oxygen transportation.
What is the first step in the process of respiration?
- A. Fermentation
- B. Krebs cycle
- C. Electron transport chain
- D. Glycolysis
Correct Answer: D
Rationale: The correct answer is Glycolysis. Glycolysis is the initial step in cellular respiration where glucose is broken down into pyruvate, producing a small amount of ATP and NADH in the cytoplasm. This step is crucial as it initiates the breakdown of glucose, setting the stage for further energy production in subsequent stages like the Krebs cycle and electron transport chain.