CLEP Biology Molecular & Cellular Biology — Questions and Answers
Question 1: What is the primary function of ribosomes in a cell?
- Energy production
- DNA replication
- Protein synthesis (Correct answer)
- Lipid storage
Correct answer: Protein synthesis
Ribosomes are cellular organelles responsible for protein synthesis, a process also known as translation. They read the genetic information encoded in messenger RNA (mRNA) and use it to assemble amino acids into specific protein sequences. This function is vital for all cellular activities, as proteins perform a vast array of roles within the cell.
Question 2: Which organelle is involved in cellular respiration?
- Chloroplast
- Nucleus
- Mitochondrion (Correct answer)
- Golgi apparatus
Correct answer: Mitochondrion
Mitochondria are often referred to as the 'powerhouses' of the cell because they are the primary sites of cellular respiration. During this process, glucose and other fuel molecules are broken down to produce adenosine triphosphate (ATP), the main energy currency of the cell.
Question 3: What is the function of the plasma membrane?
- Protein synthesis
- Structural support
- Cell division
- Regulate transport (Correct answer)
Correct answer: Regulate transport
The plasma membrane, a selectively permeable barrier, primarily functions to regulate the transport of substances into and out of the cell. It controls which molecules can pass through, maintaining the cell's internal environment and allowing for communication with its surroundings.
Question 4: Which macromolecule serves as the genetic material in most organisms?
- Lipids
- Carbohydrates
- Proteins
- DNA (Correct answer)
Correct answer: DNA
Deoxyribonucleic acid (DNA) is the macromolecule that serves as the genetic material in most organisms. It carries the hereditary instructions for the development, functioning, growth, and reproduction of all known organisms and many viruses.
Question 5: Which type of RNA carries amino acids to the ribosome?
- mRNA
- rRNA
- tRNA (Correct answer)
- snRNA
Correct answer: tRNA
Transfer RNA (tRNA) is a type of RNA molecule that plays a crucial role in protein synthesis by carrying specific amino acids to the ribosome. Each tRNA molecule has an anticodon that base-pairs with a complementary codon on the messenger RNA (mRNA), ensuring the correct amino acid is added to the growing polypeptide chain.
Question 6: Which cellular structure is found in plant cells but not in animal cells?
- Nucleus
- Mitochondrion
- Cell wall (Correct answer)
- Plasma membrane
Correct answer: Cell wall
The cell wall is a rigid outer layer found in plant cells, fungi, algae, and bacteria, but not in animal cells. Its primary function is to provide structural support, protection, and maintain the cell's turgor pressure.
Question 7: Which process results in the formation of two identical daughter cells?
- Meiosis
- Translation
- Transcription
- Mitosis (Correct answer)
Correct answer: Mitosis
Mitosis is a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus. This process is essential for growth, repair, and asexual reproduction in eukaryotic organisms, ensuring genetic continuity.
Question 8: What is the role of enzymes in biological reactions?
- Increase temperature
- Supply energy
- Slow down reactions
- Catalyze reactions (Correct answer)
Correct answer: Catalyze reactions
Enzymes are biological catalysts, meaning they speed up the rate of biochemical reactions without being consumed in the process. They achieve this by lowering the activation energy required for a reaction to occur, making life-sustaining processes possible at physiological temperatures.
Question 9: Which part of the cell cycle involves DNA replication?
- G1 phase
- S phase (Correct answer)
- G2 phase
- M phase
Correct answer: S phase
The S phase (synthesis phase) of the cell cycle is when DNA replication occurs. During this crucial stage, the cell duplicates its entire genome, ensuring that each daughter cell receives a complete and identical set of chromosomes after cell division.
CLEP Biology Molecular & Cellular Biology
What is the primary function of ribosomes in a cell?