Class 10 · Chapter 5 · Biology
Life Processes Cheat Sheet
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Photosynthesis
Green plants use carbon dioxide and water in the presence of sunlight and chlorophyll to make glucose and release oxygen.
Aerobic respiration
Glucose is broken down completely with oxygen in the mitochondria, releasing a large amount of energy.
Anaerobic respiration (yeast)
In the absence of oxygen, yeast converts glucose into ethanol and carbon dioxide.
Anaerobic respiration (muscle)
During heavy exercise, muscle cells form lactic acid; this causes cramps.
Definitions
- Nutrition
- The process of taking in food and using it for energy, growth and repair.
- Autotrophic nutrition
- Nutrition in which an organism makes its own food from simple substances; e.g. green plants.
- Heterotrophic nutrition
- Nutrition in which an organism depends on other organisms for food.
- Photosynthesis
- The process by which green plants make food using carbon dioxide, water, sunlight and chlorophyll.
- Stomata
- Tiny pores on the surface of leaves that allow exchange of gases and loss of water vapour.
- Chlorophyll
- The green pigment in plants that absorbs sunlight for photosynthesis.
- Saprophytic nutrition
- Nutrition in which an organism feeds on dead and decaying matter; e.g. Rhizopus.
- Parasitic nutrition
- Nutrition in which an organism lives on or inside another organism and takes food from it.
- Holozoic nutrition
- Nutrition in which an organism takes in whole food; e.g. Amoeba, human beings.
- Peristalsis
- Rhythmic contraction and relaxation of the gut wall that pushes food forward.
- Villi
- Finger-like projections of the small intestine that increase surface area for absorption.
- Respiration
- The process of breaking down food to release energy stored in it.
- Aerobic respiration
- Respiration that takes place in the presence of oxygen and releases more energy.
- Anaerobic respiration
- Respiration that takes place without oxygen and releases less energy.
- Translocation
- The transport of food from leaves to other parts of the plant through phloem.
- Transpiration
- The loss of water vapour from the aerial parts of a plant, mainly through stomata.
- Double circulation
- Blood passing twice through the heart in one complete cycle — pulmonary and systemic circulation.
- Excretion
- The removal of harmful nitrogenous wastes from the body.
- Nephron
- The basic filtering unit of the kidney.
- Dialysis
- An artificial method of removing wastes from blood in a patient whose kidneys have failed.
- Alveoli
- Tiny balloon-like sacs in the lungs where exchange of gases takes place.
Key Points
- The four life processes are nutrition, respiration, transportation and excretion.
- Autotrophic nutrition needs carbon dioxide, water, sunlight and chlorophyll; stomata open to let in CO₂.
- Human digestion: mouth (salivary amylase) → oesophagus → stomach (HCl, mucus and pepsin) → small intestine (bile, pancreatic and intestinal juices) → large intestine (water absorption).
- In respiration, glucose is broken down to release energy. Energy is stored in ATP, the energy currency of the cell.
- Aerobic respiration releases much more energy than anaerobic respiration; aerobic breakdown occurs in the mitochondria.
- In plants, exchange of gases occurs through stomata and lenticels; glucose formed is stored as starch.
- Human transport: the heart has four chambers; arteries carry blood away from the heart and veins bring it back; valves prevent backflow.
- Platelets help in the clotting of blood; lymph carries digested fats and drains excess tissue fluid.
- In plants, xylem carries water and minerals upward and phloem transports food; transpiration creates the pull for water.
- The kidneys filter the blood through nephrons to form urine; an artificial kidney works by dialysis.
- Plants remove wastes through transpiration and by storing them in leaves, gums, resins and latex.