Question
Which of the following cells is characterized by the presence of chloroplasts, a plasma membrane, and 80S ribosomes?
A. Bryophyte
B. Lymphocyte
C. Prokaryote
D. Neuron
▶️Answer/Explanation
Ans: A
Explanation: Bryophytes, have chloroplasts for photosynthesis, a plasma membrane for cell boundary, and 80S ribosomes for protein synthesis within the endoplasmic reticulum.
Lymphocyte: Lymphocytes are a type of white blood cell found in the immune system of animals. They lack chloroplasts as they are not involved in photosynthesis. The presence of chloroplasts rules out the possibility of the cell being a lymphocyte.
Prokaryote: Prokaryotes, such as bacteria, lack membrane-bound organelles like chloroplasts and have 70S ribosomes, not 80S. The presence of both chloroplasts and 80S ribosomes eliminates the likelihood of the cell being a prokaryote.
Neuron: Neurons are cells of the nervous system in animals. They don’t contain chloroplasts since they don’t undergo photosynthesis. Additionally, they typically have 80S ribosomes, but the presence of chloroplasts makes this option less likely for a neuron.
Question
What is the primary function of cholesterol in the plasma membranes of mammalian cells, where over 90% of cellular cholesterol is found?
A. To regulate membrane fluidity
B. To increase membrane solubility
C. To increase membrane permeability
D. To regulate membrane temperature
Answer/Explanation
Ans: A
Question
For facilitated diffusion, which of the following are necessary?
I. A concentration gradient
II. ATP
III. A channel protein
A. I only
B. I and III only
C. II and III only
D. I, II, and III
Answer/Explanation
Ans: B
Question
During the formation of the earliest cells, which cell component is believed to have emerged first?
A. Chloroplast
B. Plasma membrane
C. Mitochondria
D. Cell wall
Answer/Explanation
Ans: B
Question
During the G2 phase of a somatic cell in a chimpanzee, where the haploid chromosome number is 24, how many sister chromatids would be present?
A. 12
B. 24
C. 48
D. 96
Answer/Explanation
Ans: D