AS (7401)
Biology
Paper 1
Updated Version 2024
QNS & ANS
1. Describe the structure and function of the phospholipid bilayer in
biological cells.
- The phospholipid bilayer forms the fundamental structure of cell
membranes, consisting of two layers of phospholipids with
hydrophilic heads facing outward and hydrophobic tails facing
inward, creating a semi-permeable barrier that regulates substance
entry and exit.
2. Explain how proteins are synthesized in a cell and their subsequent
roles.
- Proteins are synthesized in a cell through the process of
transcription and translation, where genetic information from DNA is
transcribed into mRNA, which is then translated by ribosomes into
amino acid chains that fold into functional proteins that perform
various roles such as enzymes, hormones, and structural
components.
3. Discuss the role of mitochondria in energy transformation.
- Mitochondria are the powerhouse of the cell, where they convert
energy from nutrients into ATP through cellular respiration, providing
the necessary energy for various cellular processes.
4. How do cells communicate with each other in multicellular
organisms?
- Cells communicate through chemical signals such as hormones
, and neurotransmitters, which bind to specific receptors on target
cells, triggering a response that coordinates activities between
different cells and tissues.
5. What is osmosis and how does it affect cell stability?
- Osmosis is the diffusion of water across a semi-permeable
membrane from an area of low solute concentration to an area of
high solute concentration, affecting cell stability by causing cells to
swell or shrink based on the surrounding fluid's tonicity.
6. Define active transport and give an example of where it is used in
the body.
- Active transport is the movement of molecules across a cell
membrane from a lower to a higher concentration using energy, such
as the sodium-potassium pump which maintains the electrochemical
gradient in nerve cells.
7. Explain the significance of meiosis in genetic diversity.
- Meiosis is a type of cell division that reduces the chromosome
number by half, resulting in the production of genetically diverse
gametes, contributing to genetic variation in populations.
8. Describe how DNA replication ensures continuity of genetic
information.
- DNA replication is a semi-conservative process where each strand
of the original DNA molecule serves as a template for the production
of a complementary strand, ensuring that each new cell receives an
exact copy of the genetic information.
9. What is the role of enzymes in metabolic reactions?
- Enzymes act as biological catalysts that speed up metabolic
reactions by lowering the activation energy, allowing the cell to carry
out complex biochemical processes efficiently.
10. How do antigens and antibodies interact in the immune
response?
- Antigens are foreign substances that elicit an immune response,
while antibodies are proteins produced by B-cells that specifically
bind to antigens, neutralizing them or marking them for destruction
Biology
Paper 1
Updated Version 2024
QNS & ANS
1. Describe the structure and function of the phospholipid bilayer in
biological cells.
- The phospholipid bilayer forms the fundamental structure of cell
membranes, consisting of two layers of phospholipids with
hydrophilic heads facing outward and hydrophobic tails facing
inward, creating a semi-permeable barrier that regulates substance
entry and exit.
2. Explain how proteins are synthesized in a cell and their subsequent
roles.
- Proteins are synthesized in a cell through the process of
transcription and translation, where genetic information from DNA is
transcribed into mRNA, which is then translated by ribosomes into
amino acid chains that fold into functional proteins that perform
various roles such as enzymes, hormones, and structural
components.
3. Discuss the role of mitochondria in energy transformation.
- Mitochondria are the powerhouse of the cell, where they convert
energy from nutrients into ATP through cellular respiration, providing
the necessary energy for various cellular processes.
4. How do cells communicate with each other in multicellular
organisms?
- Cells communicate through chemical signals such as hormones
, and neurotransmitters, which bind to specific receptors on target
cells, triggering a response that coordinates activities between
different cells and tissues.
5. What is osmosis and how does it affect cell stability?
- Osmosis is the diffusion of water across a semi-permeable
membrane from an area of low solute concentration to an area of
high solute concentration, affecting cell stability by causing cells to
swell or shrink based on the surrounding fluid's tonicity.
6. Define active transport and give an example of where it is used in
the body.
- Active transport is the movement of molecules across a cell
membrane from a lower to a higher concentration using energy, such
as the sodium-potassium pump which maintains the electrochemical
gradient in nerve cells.
7. Explain the significance of meiosis in genetic diversity.
- Meiosis is a type of cell division that reduces the chromosome
number by half, resulting in the production of genetically diverse
gametes, contributing to genetic variation in populations.
8. Describe how DNA replication ensures continuity of genetic
information.
- DNA replication is a semi-conservative process where each strand
of the original DNA molecule serves as a template for the production
of a complementary strand, ensuring that each new cell receives an
exact copy of the genetic information.
9. What is the role of enzymes in metabolic reactions?
- Enzymes act as biological catalysts that speed up metabolic
reactions by lowering the activation energy, allowing the cell to carry
out complex biochemical processes efficiently.
10. How do antigens and antibodies interact in the immune
response?
- Antigens are foreign substances that elicit an immune response,
while antibodies are proteins produced by B-cells that specifically
bind to antigens, neutralizing them or marking them for destruction
