Nokea
Which of the following is not found within a bacterial cell?
- A. mitochondria
- B. DNA
- C. vesicles
- D. ribosome
Correct Answer: A
Rationale: Mitochondria are organelles found in eukaryotic cells, not in bacterial cells. Bacterial cells lack membrane-bound organelles like mitochondria. Choices B, C, and D are all components that can be found within a bacterial cell. DNA is the genetic material that carries the instructions for cell function, vesicles are involved in transport and storage of substances, and ribosomes are responsible for protein synthesis in bacterial cells.
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What is the function of water in photosynthesis?
- A. Combining with carbon dioxide
- B. Absorbing light energy
- C. Supplying electrons in the light reactions
- D. Transporting hydrogen ions in the dark reactions
Correct Answer: C
Rationale: Water is crucial in photosynthesis as it provides electrons during the light reactions. When water molecules are split in the light-dependent reactions, oxygen is released, and electrons are transferred to photosystem II to initiate the electron transport chain. This process is vital for the production of ATP and NADPH, which are necessary for the Calvin cycle to synthesize sugars.
How many different types of nucleotides are there in DNA?
- A. one
- B. two
- C. four
- D. eight
Correct Answer: C
Rationale: The correct answer is C: four. DNA is composed of four different types of nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). These nucleotides pair specifically (A with T and C with G) to form the double-stranded DNA structure.
Which macromolecule is an example of a nucleic acid?
- A. Glucose.
- B. DNA.
- C. Albumin.
- D. HCl.
Correct Answer: B
Rationale: Correct Answer: B - DNA
Rationale:
1. Nucleic acids are macromolecules that store genetic information.
2. DNA (Deoxyribonucleic acid) is a type of nucleic acid that carries genetic instructions.
3. Glucose (A) is a carbohydrate, not a nucleic acid.
4. Albumin (C) is a protein, not a nucleic acid.
5. HCl (D) is a compound, not a nucleic acid.
Summary:
The correct answer is B because DNA is a nucleic acid that specifically functions to store genetic information, unlike the other choices which are not nucleic acids.
Many control, both positive and negative, maintain body processes. What is this phenomenon called?
- A. Homeostasis.
- B. Endothermy.
- C. Metabolism.
- D. Respiration.
Correct Answer: A
Rationale: Correct Answer: A: Homeostasis.
Rationale:
1. Homeostasis refers to the ability of the body to maintain internal stability despite external changes.
2. It involves various control mechanisms to keep key physiological parameters within a narrow range.
3. Positive and negative feedback loops regulate processes to achieve homeostasis.
4. Choices B, C, and D do not specifically relate to the concept of maintaining internal stability like homeostasis does.
Why can animal cells use a contractile ring but plant cells cannot?
- A. Plant cells can use both methods to divide.
- B. Animal cells divide faster, requiring them to pinch apart.
- C. Plant cells are too rigid to utilize a contractile ring.
- D. Plant cells have a cell wall that hinders the formation of a contractile ring.
Correct Answer: D
Rationale: Plant cells have a rigid cell wall surrounding their cell membrane, which prevents the formation of a contractile ring during cell division. The contractile ring is a structure composed of actin filaments responsible for pinching the cell in two during cytokinesis. Since plant cells cannot form a contractile ring due to the presence of the cell wall, they rely on other methods such as cell plate formation to complete cell division.