Year 9 Biology IGCSE (Cambridge) FAQs
1. What are the main differences between plant and animal cells? |
 |
Ans.Plant cells have a cell wall, chloroplasts for photosynthesis, and a large central vacuole, while animal cells do not have these features. Animal cells have smaller vacuoles and have lysosomes that are typically absent in plant cells.
2. What is the function of the cell membrane? |
 |
Ans.The cell membrane regulates what enters and exits the cell, providing protection and support. It is selectively permeable, allowing certain substances to pass while blocking others.
3. How do enzymes function in biological processes? |
 |
Ans.Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy needed for the reaction to occur. They are specific to substrates and operate best at optimal pH and temperature.
4. What is photosynthesis, and why is it important? |
 |
Ans.Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy, producing glucose and oxygen from carbon dioxide and water. It is essential for providing energy for nearly all life on Earth.
5. What are the stages of cellular respiration? |
 |
Ans.Cellular respiration consists of three main stages: glycolysis, the Krebs cycle (citric acid cycle), and the electron transport chain. These processes convert glucose into ATP, the energy currency of the cell.
6. How does the structure of DNA relate to its function? |
 |
Ans.DNA has a double helix structure composed of nucleotide bases (adenine, thymine, cytosine, and guanine) that pair specifically. This structure allows for the accurate replication of genetic information and the coding of proteins.
7. What is the role of ribosomes in the cell? |
 |
Ans.Ribosomes are the cellular structures responsible for synthesizing proteins by translating messenger RNA (mRNA) into amino acid sequences, which are then folded into functional proteins.
8. What is the significance of mitosis and meiosis? |
 |
Ans.Mitosis is the process of cell division that results in two genetically identical daughter cells, essential for growth and repair. Meiosis is a specialized form of cell division that produces gametes (sperm and eggs) with half the genetic material, promoting genetic diversity.
9. What are the main types of biological macromolecules? |
 |
Ans.The four main types of biological macromolecules are carbohydrates, proteins, lipids, and nucleic acids. Each plays vital roles in structure, function, and regulation of the body’s tissues and organs.
10. How do organisms maintain homeostasis? |
 |
Ans.Organisms maintain homeostasis through various physiological processes that regulate internal conditions, such as temperature, pH, and electrolyte balance. Feedback mechanisms, such as negative feedback, help to restore equilibrium when there are deviations from the norm.
11. What is the role of the nervous system in living organisms? |
 |
Ans.The nervous system coordinates the actions and reactions of an organism by transmitting signals between different parts of the body. It processes sensory information and controls responses, enabling interaction with the environment.
12. Why are vaccines important for public health? |
 |
Ans.Vaccines are important because they help prevent diseases by stimulating the immune system to recognize and fight specific pathogens, reducing the incidence of infectious diseases and protecting community health through herd immunity.
13. What are the differences between asexual and sexual reproduction? |
 |
Ans.Asexual reproduction involves a single parent and produces offspring that are genetically identical to the parent, while sexual reproduction involves two parents and results in genetically diverse offspring through the combination of genetic material.
14. How do adaptations help organisms survive in their environments? |
 |
Ans.Adaptations are traits that enhance an organism's ability to survive and reproduce in its environment. They can be structural (physical features), behavioral (actions), or physiological (internal processes) and are the result of evolutionary processes.
15. What is the purpose of scientific classification in biology? |
 |
Ans.Scientific classification organizes living organisms into categories based on shared characteristics, making it easier to study and understand biodiversity. The hierarchical system includes domains, kingdoms, phyla, classes, orders, families, genera, and species.