BIOLOGY PAPER 1:

1. What is a eukaryotic cell?
A cell with a nucleus and membrane-bound organelles, found in animals, plants, fungi, and protists.

2. What is a prokaryotic cell?
A simpler cell without a nucleus, such as bacteria. DNA is free in the cytoplasm.

3. What is the function of the nucleus?
It contains genetic material and controls cell activities.

4. What is the function of mitochondria?
Site of aerobic respiration, releasing energy for the cell.

5. What is the function of ribosomes?
They are the site of protein synthesis.

6. What is the function of the cell membrane?
It controls the movement of substances in and out of the cell.

7. What is the function of the cell wall?
Provides structure and support; made of cellulose in plants.

8. What is the function of the vacuole?
Contains cell sap and maintains internal pressure in plant cells.

9. What is the function of chloroplasts?
Site of photosynthesis; contains chlorophyll to absorb light.

10. What are plasmids?
Small loops of DNA found in bacterial cells.

11. Compare light and electron microscopes.
Light microscopes have lower resolution (~1000x); electron microscopes offer much higher resolution and magnification (~500,000x).

12. What is magnification and how is it calculated?
Magnification = Image size ÷ Actual size.

13. What is resolution in microscopy?
The ability to distinguish two close objects as separate.

14. Describe binary fission.
Bacterial cell division where the cell splits into two genetically identical cells.

15. What is mitosis used for?
Growth, repair, and asexual reproduction.

16. Describe the stages of the cell cycle.
Interphase (growth and DNA replication), Mitosis (nucleus divides), Cytokinesis (cell divides).

17. What are stem cells?
Undifferentiated cells that can develop into different cell types.

18. What are embryonic stem cells?
Stem cells from early embryos that can differentiate into any cell type.

19. What are adult stem cells?
Found in bone marrow; can form certain cells like red/white blood cells and platelets.

20. What is therapeutic cloning?
Creating an embryo with the same DNA as a patient to produce matching stem cells for treatment.

21. What are ethical concerns about embryonic stem cells?
Destroying embryos to obtain stem cells raises moral and ethical questions about the start of life.

22. What is diffusion?
Movement of particles from high to low concentration.

23. Give an example of diffusion in the body.
Oxygen diffusing from alveoli into the blood in the lungs.

24. What is osmosis?
Diffusion of water across a partially permeable membrane from high water concentration to low.

25. What is active transport?
Movement of substances against a concentration gradient, requiring energy from respiration.

26. Where does active transport occur in plants?
In root hair cells to absorb mineral ions from the soil.

27. Where does active transport occur in animals?
In the small intestine to absorb glucose from the gut into the blood.

28. What is a concentration gradient?
The difference in concentration between two regions.

29. What is a partially permeable membrane?
A membrane that only allows some molecules (like water) to pass through.

30. How do surface area and volume affect diffusion?
Larger surface area to volume ratio increases the rate of diffusion.

31. What adaptations do alveoli have for gas exchange?
Large surface area, thin walls, moist lining, and good blood supply.

32. What are the adaptations of root hair cells?
Long extensions increase surface area to absorb water and mineral ions.

33. What are the adaptations of sperm cells?
Tail for movement, many mitochondria for energy, enzymes to digest egg membrane.

34. What are the adaptations of nerve cells?
Long axon for transmitting signals, branched endings (dendrites) to connect with other cells.

35. What are the adaptations of muscle cells?
Long cells that can contract, lots of mitochondria to release energy.

36. What are the adaptations of xylem cells?
Hollow and strengthened with lignin to carry water and mineral ions in one direction.

37. What are the adaptations of phloem cells?
Sieve plates and companion cells allow movement of sugars throughout the plant.

38. What is a tissue?
A group of similar cells working together to perform a specific function.

39. What is an organ?
A group of different tissues working together to perform a specific function.

40. What is an organ system?
A group of organs that work together to carry out a particular life process.

41. Give an example of an organ system.
The digestive system – breaks down food and absorbs nutrients.

42. Why is cell differentiation important?
It allows cells to specialise and carry out specific functions effectively.

43. When do most animal cells differentiate?
At an early stage in embryonic development.

44. Can plant cells differentiate throughout life?
Yes, many plant cells can continue to differentiate when needed.

45. What is a specialised cell?
A cell that has adapted structures to perform a specific job.

46. Give an example of a specialised plant cell.
Palisade cells – full of chloroplasts to maximise photosynthesis.

47. What is the function of ciliated epithelial cells?
Move mucus and trapped particles up and out of the airways.

48. What is the function of red blood cells?
Carry oxygen using haemoglobin; have no nucleus to maximise space.

49. Why don’t red blood cells have a nucleus?
To make room for more haemoglobin, increasing oxygen-carrying capacity.

50. What is haemoglobin?
A red protein in red blood cells that binds with oxygen to transport it.

51. What is the function of the digestive system?
To break down large, insoluble food molecules into smaller, soluble ones that can be absorbed into the blood.

52. What are the main parts of the digestive system?
Mouth, oesophagus, stomach, small intestine, large intestine, liver, pancreas.

53. What is the role of the mouth in digestion?
Mechanical digestion (chewing) and chemical digestion of starch by amylase.

54. What is the function of the stomach?
Produces hydrochloric acid to kill bacteria and protease (pepsin) to digest proteins.

55. What is the function of the liver in digestion?
Produces bile to neutralise stomach acid and emulsify fats.

56. What is the function of the gall bladder?
Stores and releases bile into the small intestine.

57. What is the function of the pancreas?
Produces digestive enzymes: amylase, protease, and lipase.

58. What is the function of the small intestine?
Digests and absorbs nutrients using villi for a large surface area.

59. What is the function of the large intestine?
Absorbs water from undigested food to form faeces.

60. What is the function of enzymes in digestion?
Break large, insoluble molecules into small, soluble ones.

61. What is the substrate and product of amylase?
Starch → sugars (mainly maltose)

62. Where is amylase produced?
Salivary glands, pancreas, and small intestine.

63. What is the substrate and product of protease?
Proteins → amino acids.

64. Where is protease produced?
Stomach (pepsin), pancreas, and small intestine.

65. What is the substrate and product of lipase?
Lipids → fatty acids + glycerol.

66. Where is lipase produced?
Pancreas and small intestine.

67. What is bile and what does it do?
An alkaline substance that emulsifies fats and neutralises stomach acid.

68. What is emulsification?
Breaking down large fat droplets into smaller ones to increase surface area for lipase action.

69. What are villi and what is their function?
Finger-like projections in the small intestine that absorb nutrients.

70. How are villi adapted for absorption?
Large surface area, thin walls, good blood supply.

71. What is the function of the heart?
To pump blood around the body via the circulatory system.

72. What type of circulatory system do humans have?
Double circulatory system (pulmonary and systemic circuits).

73. What is the function of the right side of the heart?
Pumps deoxygenated blood to the lungs.

74. What is the function of the left side of the heart?
Pumps oxygenated blood to the body.

75. Why does the left side of the heart have a thicker wall?
It pumps blood at higher pressure to the entire body.

76. What is the function of arteries?
Carry blood away from the heart under high pressure.

77. What is the function of veins?
Carry blood to the heart under lower pressure; contain valves.

78. What is the function of capillaries?
Exchange substances (e.g. oxygen, nutrients) between blood and tissues.

79. What are the features of red blood cells?
No nucleus, biconcave shape, contains haemoglobin to carry oxygen.

80. What are the types of white blood cells?
Phagocytes (engulf pathogens) and lymphocytes (produce antibodies).

81. What is the function of platelets?
Cell fragments that help blood clot at wounds.

82. What is the function of plasma?
Liquid component that carries blood cells, hormones, nutrients, CO₂, and urea.

83. What is coronary heart disease?
Fatty material builds up in coronary arteries, reducing blood flow to the heart muscle.

84. What are stents and how do they work?
Metal mesh tubes inserted into arteries to keep them open.

85. What are statins and what do they do?
Drugs that reduce blood cholesterol and slow down fatty deposit formation.

86. What is a faulty heart valve and how can it be treated?
A valve that doesn’t open/close properly; treated with biological or mechanical valves.

87. What is a pacemaker?
An electrical device implanted under the skin to regulate heart rhythm.

88. What is artificial blood used for?
Temporary replacement to carry oxygen after severe blood loss.

89. What are artificial hearts used for?
Short-term replacement for patients waiting for a heart transplant.

90. What is a non-communicable disease?
A disease that cannot be spread between people (e.g. cancer, CHD).

91. What lifestyle factors affect non-communicable diseases?
Smoking, alcohol, diet, lack of exercise.

92. How does smoking affect health?
Can lead to lung cancer, heart disease, and damages blood vessels.

93. How does alcohol affect health?
Causes liver damage, brain damage, and affects reaction time.

94. How does obesity affect health?
Increases risk of type 2 diabetes, high blood pressure, and CHD.

95. What is a risk factor?
Anything that increases the chance of developing a disease.

96. What is cancer?
Uncontrolled cell division that forms a tumour.

97. What is a benign tumour?
A non-cancerous growth that doesn’t spread.

98. What is a malignant tumour?
A cancerous tumour that spreads to other parts of the body.

99. How can cancer be treated?
Surgery, radiotherapy, chemotherapy.

100. What are the main plant organs?
Roots, stems, and leaves – work together for transport and photosynthesis.

101. What is a pathogen?
A microorganism that causes disease (e.g. bacteria, viruses, fungi, protists).

102. What is bacteria?
Single-celled organisms that can reproduce rapidly and release toxins to cause illness.

103. What is a virus?
Tiny particles that invade host cells and replicate inside, often killing the host cell.

104. What is a protist?
Single-celled eukaryotes; some are parasites that cause disease (e.g. malaria).

105. What is a fungus?
Organisms that can be unicellular or multicellular; some cause diseases like athlete’s foot.

106. How does measles spread and what are its symptoms?
Spread by droplets; symptoms include fever and rash; can be serious.

107. How can measles be prevented?
Vaccination in early childhood.

108. What causes HIV and what are its effects?
Caused by the Human Immunodeficiency Virus; attacks immune system leading to AIDS.

109. How is HIV transmitted?
Through bodily fluids during unprotected sex, sharing needles, or mother to baby.

110. What is the treatment for HIV?
Antiretroviral drugs suppress the virus but do not cure it.

111. What causes tobacco mosaic virus (TMV) in plants?
A virus that causes mosaic pattern on leaves and reduces photosynthesis.

112. How does salmonella cause disease?
Bacteria in contaminated food causing food poisoning (fever, cramps, vomiting, diarrhoea).

113. How can salmonella infection be prevented?
Good hygiene, cooking food thoroughly, and proper food handling.

114. What is gonorrhea?
A sexually transmitted bacterial infection causing painful urination and discharge.

115. How can gonorrhea be treated and prevented?
Treated with antibiotics; prevented by using barrier contraception like condoms.

116. What are the body's first lines of defence?
Skin, mucus membranes, tears, stomach acid, and cilia in airways.

117. How does the skin protect against infection?
Acts as a physical barrier and produces antimicrobial secretions.

118. What is the role of mucus in the respiratory tract?
Traps pathogens and particles.

119. How do cilia help prevent infection?
Beat mucus up and out of the lungs to expel trapped microbes.

120. How does stomach acid protect against pathogens?
Kills many bacteria in food and drink.

121. What are phagocytes?
White blood cells that engulf and digest pathogens by phagocytosis.

122. What are lymphocytes?
White blood cells that produce antibodies and memory cells.

123. What are antibodies?
Proteins that specifically bind to antigens on pathogens to mark them for destruction.

124. What are antigens?
Molecules on the surface of pathogens that trigger an immune response.

125. What are memory cells?
Lymphocytes that remain in the body after infection to give immunity.

126. What is vaccination?
Injecting dead or inactive pathogens to stimulate immunity without causing disease.

127. How do vaccines work?
They stimulate the immune system to produce antibodies and memory cells.

128. What are the benefits of herd immunity?
When most people are vaccinated, reducing disease spread and protecting unvaccinated individuals.

129. What are antibiotics?
Drugs that kill or inhibit bacteria but do not work against viruses.

130. Why can overuse of antibiotics be dangerous?
It can lead to antibiotic-resistant bacteria.

131. What is antibiotic resistance?
When bacteria evolve to survive antibiotic treatment, making infections harder to treat.

132. How can antibiotic resistance be reduced?
Use antibiotics only when necessary and complete prescribed courses.

133. What is the importance of developing new medicines?
To treat resistant bacteria and emerging diseases.

134. What is the role of preclinical testing?
Testing drugs on cells, tissues, and animals before human trials.

135. What are clinical trials?
Testing drugs on healthy volunteers and patients to check safety and effectiveness.

136. What is the placebo effect?
When patients feel better after taking a fake drug because they expect to.

137. What is the role of double-blind trials?
Neither doctors nor patients know who receives the real drug to avoid bias.

138. What is monoclonal antibody therapy?
Using lab-made antibodies designed to target specific molecules on cancer or infected cells.

139. How are monoclonal antibodies used in pregnancy tests?
They bind to hormones in urine to produce a visible line.

140. How can plant diseases affect crop yields?
They reduce growth and productivity by damaging plant tissues.

141. What is the role of nitrate ions in plants?
Needed to make proteins and grow.

142. What happens if a plant is nitrate-deficient?
Poor growth and yellow leaves.

143. What is the role of magnesium ions in plants?
Needed to make chlorophyll for photosynthesis.

144. What happens if a plant is magnesium-deficient?
Yellow leaves (chlorosis) and reduced photosynthesis.

145. What are aphids and how do they harm plants?
Insects that feed on plant sap, weakening plants and spreading disease.

146. How can plants be protected from pests and diseases?
Using pesticides, biological control, crop rotation, and resistant varieties.

147. What is biological control?
Using natural predators or parasites to control pests.

148. What are the disadvantages of chemical pesticides?
They can harm wildlife, cause pollution, and lead to resistance.

149. What is crop rotation?
Growing different crops in cycles to reduce pest buildup and improve soil nutrients.

150. How can plant diseases be diagnosed?
Observing symptoms, laboratory tests, and using technology like ELISA kits.

151. What is the word equation for photosynthesis?
Carbon dioxide + water → glucose + oxygen

152. What is the balanced symbol equation for photosynthesis?
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

153. Where does photosynthesis occur?
In the chloroplasts of plant cells.

154. What pigment is essential for photosynthesis?
Chlorophyll.

155. What type of reaction is photosynthesis?
Endothermic – it requires energy from sunlight.

156. What are the limiting factors of photosynthesis?
Light intensity, carbon dioxide concentration, and temperature.

157. How does light affect the rate of photosynthesis?
More light increases rate up to a point, then levels off.

158. How does CO₂ concentration affect photosynthesis?
Increases rate until another factor becomes limiting.

159. How does temperature affect photosynthesis?
Rate increases with temperature until enzymes denature.

160. What is the effect of chlorophyll amount on photosynthesis?
Less chlorophyll (e.g. due to disease) = lower photosynthesis rate.

161. How is glucose used in plants?
For respiration, making cellulose, amino acids, storing as starch, and fats/oils.

162. Why is glucose converted into starch in plants?
Starch is insoluble and better for storage.

163. How are amino acids formed in plants?
Glucose + nitrate ions = amino acids (for protein synthesis).

164. What conditions are needed for photosynthesis to be efficient?
Warm temperature, adequate light, and sufficient CO₂.

165. What is a greenhouse used for?
To control environmental conditions and optimise plant growth.

166. What is the inverse square law in photosynthesis?
Light intensity ∝ 1 ÷ (distance)² – used to calculate how light levels drop with distance.

167. How can CO₂ levels be increased in a greenhouse?
Using a paraffin heater or CO₂ pump.

168. How can temperature be controlled in a greenhouse?
Using heaters and ventilation systems.

169. What is a hydroponic system?
Growing plants in nutrient-rich solutions without soil.

170. What is respiration?
The process of releasing energy from glucose.

171. What is the word equation for aerobic respiration?
Glucose + oxygen → carbon dioxide + water (+ energy)

172. What is the balanced symbol equation for aerobic respiration?
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

173. Where does aerobic respiration occur?
In the mitochondria of cells.

174. What is the energy released in respiration used for?
Muscle contraction, active transport, maintaining body temperature, making larger molecules.

175. What is anaerobic respiration?
Respiration without oxygen – releases less energy.

176. What is the word equation for anaerobic respiration in animals?
Glucose → lactic acid (+ energy)

177. Why does anaerobic respiration release less energy?
Glucose is only partially broken down.

178. What is the word equation for anaerobic respiration in yeast?
Glucose → ethanol + carbon dioxide

179. What is fermentation?
Anaerobic respiration in yeast, used in making bread and alcohol.

180. Why does bread rise during fermentation?
CO₂ released by yeast causes dough to expand.

181. What is oxygen debt?
The extra oxygen required to remove lactic acid after anaerobic respiration.

182. How is lactic acid removed from the body?
Transported to the liver to be broken down.

183. What happens to breathing rate after exercise?
Increases to deliver more oxygen to muscles and repay oxygen debt.

184. What happens to heart rate during exercise?
Increases to pump more oxygenated blood to muscles.

185. What is metabolism?
The sum of all chemical reactions in a cell or organism.

186. Give an example of a metabolic reaction.
Converting glucose into glycogen (storage molecule in animals).

187. What is glycogen?
A storage form of glucose in animals, especially in liver and muscles.

188. How do metabolic rates vary?
By age, activity level, genetics, and muscle mass.

189. How is body temperature maintained during cold conditions?
Increased respiration in muscles generates heat.

190. Why do plants convert glucose into cellulose?
To strengthen cell walls.

191. Why do plants store energy as fats or oils?
For long-term energy storage, especially in seeds.

192. What are the effects of exercise on muscles?
Muscles contract more, use more energy, may fatigue and build up lactic acid.

193. What is the liver’s role in respiration and recovery?
Breaks down lactic acid and stores glycogen.

194. What factors affect metabolic rate?
Muscle-to-fat ratio, hormones (like thyroxine), genetics, and activity level.

195. What happens to blood vessels in muscles during exercise?
They dilate to increase blood flow and oxygen delivery.

196. How can you investigate the effect of light on photosynthesis?
Use pondweed (e.g. Elodea) and count oxygen bubbles at different distances.

197. What precautions improve reliability of a photosynthesis practical?
Keep temperature and CO₂ constant; repeat and average results.

198. Why is sodium hydrogen carbonate used in photosynthesis experiments?
To provide a constant source of carbon dioxide.

199. What is the role of ATP in cells?
It stores and supplies energy for cellular processes.

200. What is the main difference between aerobic and anaerobic respiration?
Aerobic uses oxygen and releases more energy; anaerobic does not and produces lactic acid or ethanol.