Nokea
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.
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The structure of a bacteria is circular. Which bacteria fits this criteria?
- A. Mycobacterium.
- B. Actinomyces.
- C. Clostridium.
- D. Neisseria.
Correct Answer: C
Rationale: Rationale:
1. The correct answer is C: Clostridium.
2. Clostridium is a type of bacteria that has a circular structure known as a plasmid.
3. Plasmids are small, circular DNA molecules found in bacteria.
4. Mycobacterium (A) has a rod-shaped structure with a linear chromosome.
5. Actinomyces (B) has a filamentous structure, not circular.
6. Neisseria (D) has a diplococci shape, not circular.
In summary, Clostridium fits the criteria of having a circular structure due to its plasmid, making it the correct choice.
Which characteristic is true of prokaryotic cells?
- A. Have a nucleus
- B. Have a capsule
- C. Have membrane-bound organelles
- D. Cannot move on their own
Correct Answer: B
Rationale: Prokaryotic cells are characterized by the absence of a nucleus; instead, they have a nucleoid region where the genetic material is located. Prokaryotic cells often have a capsule, a protective layer outside the cell wall that plays a role in protection and adherence to surfaces. While eukaryotic cells have membrane-bound organelles, prokaryotic cells lack these membrane-bound structures. Prokaryotic cells are capable of movement, facilitated by structures like flagella or pili.
A plant cell is placed in a solution and it shrinks from water loss. In what type of environment was the cell placed?
- A. Plasmolytic
- B. Hypertonic.
- C. Hypotonic.
- D. Isosmotic.
Correct Answer: B
Rationale: Correct Answer: B - Hypertonic
Rationale:
1. A hypertonic solution has a higher solute concentration than the cell, causing water to move out of the cell by osmosis.
2. Water loss results in the cell shrinking, as observed in this scenario.
3. Plasmolytic refers to the process of cytoplasm shrinking due to water loss in a hypertonic environment.
4. Hypotonic and isosmotic environments would not cause the cell to shrink from water loss.
Which of the following statements about antibiotics is not true?
- A. They can interfere with the bacteria's ability to survive
- B. They can affect how bacteria multiply
- C. They can cause more bacteria to grow
- D. They only work on bacteria
Correct Answer: C
Rationale: Antibiotics are medications used to treat bacterial infections by either killing the bacteria or inhibiting their growth. Options A and B correctly describe the mechanisms of action of antibiotics, making them true statements. Option C is incorrect as antibiotics are meant to reduce bacterial growth, not cause more bacteria to grow. Option D is also true as antibiotics specifically target bacterial infections and do not work on viruses or other pathogens.
Select the cell parts that are present in plant cells but not animal cells (there may be more than one answer):
- A. Cell membrane
- B. Cell wall
- C. Ribosome
- D. Chloroplast
Correct Answer: D
Rationale: Chloroplasts are unique to plant cells and are responsible for photosynthesis, a process that converts light energy into chemical energy. Animal cells do not contain chloroplasts as they do not perform photosynthesis. Therefore, the correct answer is D - Chloroplast. The cell membrane is found in both plant and animal cells, serving as a protective barrier, while the cell wall is a rigid structure present in plant cells that provides support and protection. Ribosomes are cellular structures responsible for protein synthesis and are present in both plant and animal cells.