Nokea
Which of the following cell types lacks a nucleus?
- A. platelet
- B. red blood cell
- C. white blood cell
- D. phagocyte
Correct Answer: B
Rationale: The correct answer is red blood cell (choice B). Red blood cells, also known as erythrocytes, lack a nucleus at maturity in humans. The absence of a nucleus allows these cells to carry oxygen more efficiently by maximizing space for hemoglobin, the oxygen-carrying protein. Platelets (choice A), white blood cells (choice C), and phagocytes (choice D) all have nuclei. Platelets are involved in blood clotting, white blood cells are part of the immune system, and phagocytes specialize in engulfing and digesting cellular debris and pathogens.
You may also like to solve these questions
In a population of dogs, fur color is controlled by two alleles: black (B) and tan (b). The black allele shows complete dominance. If a dog has a tan fur phenotype, what is its genotype?
- A. BB
- B. Bb
- C. bb
- D. Not enough information
Correct Answer: C
Rationale: If a dog displays a tan fur phenotype, it indicates that the dog possesses two tan alleles, represented by the genotype bb. In this case, the dog cannot have any black alleles (B) since the black allele demonstrates complete dominance over the tan allele. Therefore, the correct genotype for a dog with a tan fur phenotype is bb.
In the example provided in question 23, which type of solution is the egg placed in?
- A. Hypertonic
- B. Isotonic
- C. Hypotonic
- D. None of the above
Correct Answer: A
Rationale: When an egg is placed in a hypertonic solution, there is a higher concentration of solutes outside the egg compared to inside. This concentration gradient causes water to move out of the egg through osmosis, leading to the egg shrinking or shriveling due to the loss of water. Therefore, the correct answer is 'Hypertonic.'
What type of bond bonds one molecule of water with another molecule of water?
- A. Ionic
- B. Covalent
- C. Hydrogen
- D. Molecular
Correct Answer: C
Rationale: Two molecules of water are bonded through hydrogen bonding. This type of bond forms between the slightly positive hydrogen atom in one water molecule and the slightly negative oxygen atom in another water molecule. Hydrogen bonds are weaker than covalent bonds but are essential in various biological processes and properties of water, contributing to its unique characteristics like high surface tension, cohesion, and adhesion.
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.
Which of the following is a benefit of the intermolecular hydrogen bonding of water? (Select one that doesn't apply.)
- A. Water has a relatively high specific heat capacity.
- B. Water has strong cohesive and adhesive properties.
- C. Polarity of water allows it to act as a versatile solvent.
- D. Water moves from higher to lower concentrations.
Correct Answer: D
Rationale: The process described in option D, 'Water moves from higher to lower concentrations,' is not a direct benefit of intermolecular hydrogen bonding of water. Rather, this movement of water from higher to lower concentrations is attributed to osmosis, a phenomenon driven by differences in solute concentrations across a semi-permeable membrane. The other options, A, B, and C, directly result from water's intermolecular hydrogen bonding. Water's high specific heat capacity (A) is due to the hydrogen bonds, which allow water to absorb and release large amounts of heat with minimal temperature change. The strong cohesive and adhesive properties of water (B) are a result of hydrogen bonding, enabling water to stick to other substances. Lastly, the polarity of water (C) due to hydrogen bonding makes it an effective solvent by interacting with various solutes.