ATDH - Admission Test for Dental Hygiene Cellular and Molecular Biology Questions and Answers — Questions and Answers
Question 1: Which of the following best describes the primary outcome of meiosis?
- Two diploid cells that are genetically identical to the parent cell.
- Four diploid cells that are genetically different from the parent cell.
- Two haploid cells that are genetically identical to the parent cell.
- Four haploid cells that are genetically different from the parent cell. (Correct answer)
Correct answer: Four haploid cells that are genetically different from the parent cell.
Meiosis is a specialized type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell and from each other. This is in contrast to mitosis, which produces two genetically identical diploid cells.
Question 2: A patient has a genetic disorder that prevents their cells from properly synthesizing proteins. A defect in which organelle would most directly cause this issue by failing to 'read' the mRNA transcript?
- Mitochondrion
- Ribosome (Correct answer)
- Lysosome
- Golgi apparatus
Correct answer: Ribosome
The ribosome is the cellular machinery responsible for translation, the process of synthesizing a protein from an mRNA template. The ribosome reads the codons on the mRNA strand and facilitates the linking of amino acids brought by tRNA to form a polypeptide chain. A defect in ribosomes would directly impair protein synthesis.
Question 3: In the fluid mosaic model of the cell membrane, what is the primary function of integral proteins?
- To provide a rigid structure and shape to the cell membrane.
- To transport molecules across the membrane and act as receptors. (Correct answer)
- To synthesize ATP for cellular energy requirements.
- To store genetic information for cell replication.
Correct answer: To transport molecules across the membrane and act as receptors.
Integral proteins are embedded within the phospholipid bilayer and play crucial roles as channels or transporters for substances that cannot freely diffuse across the membrane, such as ions and glucose. They also function as receptors for cell signaling.
Question 4: During DNA replication, one enzyme is responsible for unwinding the double helix by breaking the hydrogen bonds between the nucleotide base pairs. Which enzyme performs this critical function?
- DNA Ligase
- RNA Polymerase
- DNA Helicase (Correct answer)
- DNA Polymerase
Correct answer: DNA Helicase
DNA Helicase is the enzyme that 'unzips' the two strands of the DNA double helix, creating the replication fork where replication can begin. DNA Polymerase then synthesizes the new strands, and DNA Ligase joins fragments together.
Question 5: A cell needs to move calcium ions from the cytoplasm, where the concentration is low, into the sarcoplasmic reticulum, where the concentration is high. This process requires energy. Which mechanism of cellular transport is being used?
- Facilitated Diffusion
- Osmosis
- Active Transport (Correct answer)
- Simple Diffusion
Correct answer: Active Transport
Active transport is the movement of substances across a cell membrane against their concentration gradient (from a region of lower concentration to a region of higher concentration). This process requires cellular energy, typically in the form of ATP. The other options are forms of passive transport, which do not require energy.
Question 6: Which organelle contains hydrolytic enzymes and is responsible for breaking down cellular waste, debris, and invading pathogens like bacteria?
- Peroxisome
- Endoplasmic Reticulum
- Golgi Apparatus
- Lysosome (Correct answer)
Correct answer: Lysosome
Lysosomes are membrane-bound organelles that function as the cell's digestive system. They contain a variety of acid hydrolases capable of breaking down proteins, nucleic acids, lipids, and carbohydrates. They degrade materials taken in from outside the cell and digest obsolete components of the cell itself in a process called autophagy.
ATDH - Admission Test for Dental Hygiene Cellular and Molecular Biology Questions and Answers
Which of the following best describes the primary outcome of meiosis?