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Biology: Questions and Answers

Biology revision questions and answers cover fundamental concepts such as cellular processes, genetics, physiology, ecology, and biotechnology, providing a comprehensive review for students preparing for the Zambian GCE Biology exam. Image by Plant cell structure Icelandic text.png

Questions and Answers 

1. Describe the process of photosynthesis and explain its importance in the ecosystem.
  • Ans: Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy, carbon dioxide, and water into glucose and oxygen. It is important because it is the primary source of energy for most living organisms and produces oxygen as a byproduct, which is essential for aerobic respiration and life on Earth. Read: The Process of Photosynthesis
2. Compare and contrast mitosis and meiosis, highlighting their roles in cellular reproduction.
  • Ans: 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. It is involved in growth, repair, and asexual reproduction. Meiosis is a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, and it is involved in sexual reproduction, producing gametes (sperm and egg cells). Read: Mitosis vs. Meiosis
3. Discuss the structure and function of DNA, including its role in inheritance.
  • Ans: DNA (deoxyribonucleic acid) is a molecule that contains the genetic instructions for the development, functioning, growth, and reproduction of all known organisms. Its structure consists of a double helix made up of nucleotides, and its function is to store and transmit genetic information from one generation to the next. Read: Decoding the Blueprint of Life
4. Explain the process of protein synthesis, including transcription and translation.
  • Ans: Protein synthesis is the process by which cells build proteins using information encoded in DNA. It involves two main stages: transcription, where a strand of DNA is copied into a complementary RNA molecule, and translation, where the RNA molecule is used to assemble amino acids into a polypeptide chain, which then folds into a functional protein. Read: The Intricate Dance of Protein Synthesis 
5. Describe the structure and function of cell organelles such as the nucleus, mitochondria, and chloroplasts.
  • Ans: Cell organelles such as the nucleus contain genetic material and control cellular activities. Mitochondria are the powerhouse of the cell, producing energy through cellular respiration. Chloroplasts are found in plant cells and are responsible for photosynthesis, converting light energy into chemical energy in the form of glucose. Read: Exploring the Architectures and Roles of Cell Organelles
6. Discuss the principles of Mendelian genetics, including Punnett squares and inheritance patterns.
  • Ans: Mendelian genetics is based on the principles of inheritance proposed by Gregor Mendel. These principles include the law of segregation, which states that alleles segregate randomly during gamete formation, and the law of independent assortment, which states that alleles for different traits are distributed to gametes independently of one another.
7. Explain the concept of evolution by natural selection and provide evidence to support this theory.
  • Ans: Evolution by natural selection is the process by which organisms with traits better suited to their environment are more likely to survive and reproduce, passing on those favorable traits to their offspring. Evidence supporting this theory includes fossil records, comparative anatomy, embryology, and molecular biology.
8. Discuss the impact of human activities on the environment, including deforestation and pollution.
  • Ans: Human activities such as deforestation, pollution, overfishing, and habitat destruction have negative impacts on the environment, including loss of biodiversity, habitat degradation, climate change, and disruption of ecosystems.
9. Describe the structure and function of the respiratory system, including gas exchange in the lungs.
  • Ans: The respiratory system includes organs such as the lungs, trachea, bronchi, and diaphragm. Its function is to exchange oxygen and carbon dioxide between the body and the environment, allowing for cellular respiration and the release of energy from glucose. Read: Structure and Function of the Respiratory System
10. Explain the process of digestion, including the role of enzymes and absorption in the small intestine.
  • Ans: Digestion is the process by which food is broken down into smaller molecules that can be absorbed and used by the body. It involves mechanical and chemical digestion in the mouth, stomach, and small intestine, where enzymes break down food into nutrients that can be absorbed into the bloodstream.
11. Discuss the function of the circulatory system, including the roles of the heart, blood vessels, and blood.
  • Ans: The circulatory system is responsible for transporting oxygen, nutrients, hormones, and waste products throughout the body. It consists of the heart, blood vessels (arteries, veins, and capillaries), and blood. The heart pumps oxygen-rich blood to the body's tissues through arteries and returns oxygen-poor blood to the heart through veins.
12. Describe the process of osmosis and diffusion, including their importance in maintaining cellular homeostasis.
  • Ans: Osmosis is the movement of water molecules across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration. Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration. These processes are important for maintaining the balance of water and solutes within cells and across cell membranes.
13. Explain the role of hormones in the human body, including their effects on growth, metabolism, and reproduction.
  • Ans: Hormones are chemical messengers produced by endocrine glands that regulate various physiological processes in the body, including growth, metabolism, reproduction, and homeostasis. Examples of hormones include insulin, which regulates blood sugar levels, and estrogen and testosterone, which regulate sexual development and reproduction.
14. Discuss the structure and function of the nervous system, including the transmission of nerve impulses.
  • Ans: The nervous system controls and coordinates body functions through the transmission of nerve impulses. It consists of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves that extend throughout the body). Nerve impulses are transmitted between neurons through electrical signals and chemical neurotransmitters.
15. Describe the stages of the cell cycle and explain the importance of cell division in growth and repair.
  • Ans: The cell cycle consists of interphase (G1, S, and G2 phases) and mitosis (prophase, metaphase, anaphase, and telophase/cytokinesis). Interphase is the period of growth and DNA replication, while mitosis is the process of cell division that produces two identical daughter cells. Cell division is important for growth, repair, and reproduction.
16. Discuss the ecological relationships between organisms, including competition, predation, and symbiosis.
  • Ans: Ecological relationships between organisms include competition, where organisms compete for limited resources such as food, water, and shelter; predation, where one organism (predator) hunts and feeds on another organism (prey); and symbiosis, where two or more species live closely together, often benefiting one or both species.
17. Explain the concept of biodiversity and discuss the importance of preserving it.
  • Ans: Biodiversity refers to the variety of life forms on Earth, including species diversity, genetic diversity, and ecosystem diversity. It is important for maintaining ecosystem stability, resilience, and productivity, as well as providing ecosystem services such as clean air and water, pollination, and nutrient cycling.
18. Describe the process of excretion in humans, including the roles of the kidneys, liver, and urinary system.
  • Ans: Excretion is the process of removing waste products and toxins from the body. In humans, the kidneys filter blood to remove waste products and excess substances, which are excreted as urine. The liver also plays a role in excretion by breaking down toxins and converting them into less harmful substances that can be excreted.
19. Discuss the impact of biotechnology on society, including genetic engineering and its ethical implications.
  • Ans: Biotechnology involves the manipulation of living organisms or their components to produce useful products or processes. Genetic engineering is a type of biotechnology that involves modifying the genetic material of organisms to achieve desired traits, such as disease resistance in crops or insulin production in bacteria.
20. Explain the process of homeostasis and give examples of how organisms maintain internal balance.
  • Ans: Homeostasis is the ability of organisms to maintain internal stability and balance in response to changes in the external environment. Examples include thermoregulation to maintain body temperature, osmoregulation to maintain water balance, and pH regulation to maintain proper acidity levels in the body.
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