Nokea
Where is DNA stored?
- A. The nucleus
- B. Ribosomes
- C. Endoplasmic reticulum
- D. Mitochondria
Correct Answer: A
Rationale: DNA, the genetic material of a cell, is stored within the nucleus. The nucleus serves as the control center of the cell and houses the DNA, which contains the instructions for building and maintaining the cell's structures and functions. Ribosomes are involved in protein synthesis, the endoplasmic reticulum plays a role in protein and lipid synthesis, while mitochondria are responsible for energy production through cellular respiration. Therefore, the correct answer is the nucleus where DNA is securely contained and regulated.
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What cellular appendage enables cells to move through their environments?
- A. Flagellum
- B. Cell membrane
- C. Transport protein
- D. Receptor
Correct Answer: A
Rationale: The flagellum is a whip-like appendage found in certain cells like sperm cells and some bacteria, enabling them to move through their environments. It plays a crucial role in locomotion by allowing cells to swim or propel themselves in liquids, aiding in their movement and navigation.
Why is the nucleus important in a cell?
- A. It stores the DNA.
- B. It provides structural support.
- C. It synthesizes proteins.
- D. It produces energy from food.
Correct Answer: A
Rationale: The correct answer is A. The nucleus is crucial in a cell because it stores the DNA, which contains the genetic information necessary for directing the cell's activities and determining its characteristics. The nucleus does not provide structural support, synthesize proteins, or produce energy from food; these functions are carried out by other cell organelles. Therefore, the main role of the nucleus is to safeguard and regulate the genetic material of the cell, ensuring proper cell function and inheritance of traits.
Where does anaerobic respiration happen and why?
- A. Animals; they require energy
- B. Plants; they undergo photosynthesis
- C. Bacteria; they inhabit environments with low oxygen levels
- D. None of the above
Correct Answer: C
Rationale: Anaerobic respiration occurs in bacteria as they live in environments with low oxygen levels. In the absence of oxygen, bacteria resort to anaerobic respiration to produce energy. In contrast, animals and plants predominantly rely on aerobic respiration, which necessitates oxygen. Therefore, option C is correct as it accurately identifies the primary environment where anaerobic respiration takes place.
Why does cytokinesis occur?
- A. To duplicate DNA
- B. To convert energy within organelles
- C. To eliminate bacteria
- D. To divide daughter cells
Correct Answer: D
Rationale: Cytokinesis is the process of cell division following mitosis, where the cytoplasm of a cell is split into two daughter cells. The main purpose of cytokinesis is to physically separate the newly formed nuclei and organelles into individual cells, ensuring that each daughter cell receives a complete set of cellular components to function independently. Therefore, the correct answer is D, as the primary outcome of cytokinesis is the division of daughter cells.
Which of the following structures is not directly involved in translation?
- A. tRNA
- B. mRNA
- C. ribosome
- D. DNA
Correct Answer: D
Rationale: Translation is the process of protein synthesis where mRNA is decoded to produce a specific polypeptide chain. tRNA brings amino acids to the ribosome, and the ribosome is the site where translation occurs. DNA is not directly involved in translation; instead, it serves as the genetic material that stores the instructions for protein synthesis but does not play a direct role in the protein synthesis machinery.