AS (7401)
Biology
Paper 2
Updated Version 2024
QNS & ANS
1. Describe the structure of a phospholipid and its role in cell
membranes.
- A phospholipid has a hydrophilic (water-attracting) head and
two hydrophobic (water-repelling) tails. It forms the bilayer of
cell membranes, providing a barrier that separates the cell from
its environment.
2. Explain how proteins are transported within a cell.
- Proteins are transported within a cell via vesicles that bud off
from the rough endoplasmic reticulum and fuse with the Golgi
apparatus for modification and sorting.
3. Discuss the process of osmosis and its importance to cells.
- Osmosis is the diffusion of water across a semipermeable
membrane from an area of low solute concentration to an area
of high solute concentration. It is crucial for maintaining cell
turgidity and homeostasis.
4. How do cells communicate with each other?
- Cells communicate through chemical signals such as
hormones, neurotransmitters, and cytokines, which bind to
specific receptors on target cells, triggering a response.
5. What is the significance of mitosis in multicellular organisms?
- Mitosis is the process of cell division that results in two
genetically identical daughter cells. It is essential for growth,
, development, and tissue repair in multicellular organisms.
6. Describe the role of enzymes in metabolic reactions.
- Enzymes act as biological catalysts that speed up metabolic
reactions by lowering the activation energy required for the
reaction to occur.
7. How do guard cells regulate gas exchange in plants?
- Guard cells control the opening and closing of stomata,
thereby regulating gas exchange and water loss through
transpiration in plants.
8. What is the role of mRNA in protein synthesis?
- mRNA carries the genetic code from DNA to the ribosome,
where it is translated into a specific sequence of amino acids to
form a protein.
9. Explain the process of active transport and its energy
requirements.
- Active transport is the movement of substances across a cell
membrane against their concentration gradient, requiring
energy in the form of ATP.
10. How does DNA replication ensure genetic continuity?
- DNA replication creates an exact copy of the DNA in the
nucleus, ensuring that each new cell has the same genetic
information as the parent cell.
11. Discuss the impact of mutations on genetic variation.
- Mutations introduce new genetic variations by altering DNA
sequences, which can lead to new traits and increased diversity
within a population.
12. What is the role of tRNA in translation?
- tRNA brings the appropriate amino acid to the ribosome
and matches its anticodon with the codon on the mRNA during
protein synthesis.
13. How do organisms maintain homeostasis in fluctuating
environmental conditions?
- Organisms maintain homeostasis through feedback
mechanisms that regulate processes such as temperature, pH,
Biology
Paper 2
Updated Version 2024
QNS & ANS
1. Describe the structure of a phospholipid and its role in cell
membranes.
- A phospholipid has a hydrophilic (water-attracting) head and
two hydrophobic (water-repelling) tails. It forms the bilayer of
cell membranes, providing a barrier that separates the cell from
its environment.
2. Explain how proteins are transported within a cell.
- Proteins are transported within a cell via vesicles that bud off
from the rough endoplasmic reticulum and fuse with the Golgi
apparatus for modification and sorting.
3. Discuss the process of osmosis and its importance to cells.
- Osmosis is the diffusion of water across a semipermeable
membrane from an area of low solute concentration to an area
of high solute concentration. It is crucial for maintaining cell
turgidity and homeostasis.
4. How do cells communicate with each other?
- Cells communicate through chemical signals such as
hormones, neurotransmitters, and cytokines, which bind to
specific receptors on target cells, triggering a response.
5. What is the significance of mitosis in multicellular organisms?
- Mitosis is the process of cell division that results in two
genetically identical daughter cells. It is essential for growth,
, development, and tissue repair in multicellular organisms.
6. Describe the role of enzymes in metabolic reactions.
- Enzymes act as biological catalysts that speed up metabolic
reactions by lowering the activation energy required for the
reaction to occur.
7. How do guard cells regulate gas exchange in plants?
- Guard cells control the opening and closing of stomata,
thereby regulating gas exchange and water loss through
transpiration in plants.
8. What is the role of mRNA in protein synthesis?
- mRNA carries the genetic code from DNA to the ribosome,
where it is translated into a specific sequence of amino acids to
form a protein.
9. Explain the process of active transport and its energy
requirements.
- Active transport is the movement of substances across a cell
membrane against their concentration gradient, requiring
energy in the form of ATP.
10. How does DNA replication ensure genetic continuity?
- DNA replication creates an exact copy of the DNA in the
nucleus, ensuring that each new cell has the same genetic
information as the parent cell.
11. Discuss the impact of mutations on genetic variation.
- Mutations introduce new genetic variations by altering DNA
sequences, which can lead to new traits and increased diversity
within a population.
12. What is the role of tRNA in translation?
- tRNA brings the appropriate amino acid to the ribosome
and matches its anticodon with the codon on the mRNA during
protein synthesis.
13. How do organisms maintain homeostasis in fluctuating
environmental conditions?
- Organisms maintain homeostasis through feedback
mechanisms that regulate processes such as temperature, pH,
