Nokea
What substances make up the bilayer of the cellular membrane?
- A. Nucleic acids
- B. Phospholipids
- C. Proteins
- D. Carbohydrates
Correct Answer: B
Rationale: The cellular membrane consists of a bilayer of phospholipids. This phospholipid bilayer forms a flexible barrier around the cell, providing structural integrity and fluidity. While proteins and carbohydrates are also present in the cell membrane, the main component of the membrane's structure is the phospholipid bilayer, which plays a crucial role in maintaining the cell's functions.
You may also like to solve these questions
Which combination of cell cycle phase and descriptor is correct?
- A. S phase - the cell synthesizes DNA and doubles its cytoplasm
- B. G� phase - the amount of chromosomes is doubled
- C. GÄ‚‚ phase - the phase prior to the start of mitosis in which the cell continues to grow in size and make proteins
- D. Interphase - the cell increases in mass and number of organelles to prepare for cell division
Correct Answer: C
Rationale: The correct answer is C. The GÄ‚‚ phase is the phase before mitosis within interphase where the cell grows in size and synthesizes proteins needed for cell division. Option A incorrectly describes the S phase, which is primarily for DNA synthesis. Option B is incorrect as the doubling of chromosomes does not occur in GÄ‚� phase. Option D is inaccurate because interphase encompasses GÄ‚�, S, and GÄ‚‚ phases, during which the cell prepares for division by increasing its mass and organelles, rather than specifically focusing on mitosis preparation.
A mother is homozygous recessive for freckles (ff) and a father is heterozygous for freckles (FF). Which genotypic ratio for freckles do their children have?
- A. 50% ff, 50% FF.
- B. 25% ff, 75% Ff.
- C. 25% FF, 75% ff.
- D. 50% ff, 50% Ff.
Correct Answer: A
Rationale: Correct Answer: A (50% ff, 50% FF)
Rationale:
1. The mother is homozygous recessive (ff) and the father is heterozygous (FF).
2. The father can only pass on the dominant allele (F) to all offspring.
3. All offspring will inherit one F allele from the father and one f allele from the mother.
4. The genotypic ratio will be 50% FF (f from father) and 50% ff (f from mother).
Summary:
- Choice B is incorrect because the father cannot pass on the recessive allele.
- Choice C is incorrect as the mother is homozygous recessive.
- Choice D is incorrect because it does not consider the father's genotype.
What type of bond holds water molecules together?
- A. Ionic
- B. Covalent
- C. Hydrogen
- D. Molecular
Correct Answer: C
Rationale: The correct answer is 'Hydrogen.' Water molecules are held together by hydrogen bonds. These bonds form between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another water molecule. While hydrogen bonds are weaker than covalent bonds, they play a crucial role in various biological processes, such as the cohesion of water molecules and the unique properties of water as a solvent.
What must any solution injected into tissues be to prevent cells from shrinking or swelling?
- A. Distilled.
- B. Hypertonic.
- C. Hypotonic.
- D. Isotonic.
Correct Answer: D
Rationale: The correct answer is D: Isotonic. An isotonic solution has the same concentration of solutes as the cells in the tissues, preventing them from shrinking or swelling. If a solution is hypertonic (choice B), it has a higher solute concentration and would cause cells to shrink due to water leaving the cells. A hypotonic solution (choice C) has a lower solute concentration and would cause cells to swell as water enters the cells. Distilled water (choice A) lacks solutes and would cause cells to swell. Overall, an isotonic solution maintains cell volume and prevents any osmotic imbalances.
How does a bacterium reproduce?
- A. Mitosis
- B. Meiosis
- C. Binary fission
- D. Cytokinesis
Correct Answer: C
Rationale: Bacteria reproduce through binary fission, a process in which a single bacterium divides into two identical daughter cells. Mitosis and meiosis are processes specific to eukaryotic cells, not bacteria. Cytokinesis is the final step of the cell cycle where the cytoplasm divides, but it is not the primary reproductive method for bacteria.