Class 10 Life Processes: cheat sheet

Key ideas

• Plants make food by photosynthesis, using sunlight, chlorophyll, carbon dioxide and water; gases pass through stomata.
• In humans, digestion starts in the mouth (salivary amylase), continues in the stomach (HCl and pepsin) and finishes in the small intestine, where villi absorb the food.
• Aerobic respiration in the mitochondria breaks glucose into carbon dioxide and water and releases much energy (ATP).
• Without oxygen, yeast makes ethanol and carbon dioxide, and tired muscles make lactic acid.
• The human heart has four chambers and blood passes through it twice in each circuit (double circulation).
• Arteries carry blood away from the heart; veins carry it back. In plants, xylem carries water and phloem carries food.
• The kidneys filter the blood in nephrons and make urine; useful substances are taken back.

Remember

Watch out

• Saying all arteries carry oxygen-rich blood: the pulmonary artery carries blood low in oxygen to the lungs.
• Mixing up xylem (water) and phloem (food).
• Thinking plants only photosynthesise and never respire (they respire all the time).

Worked example

Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in sunlight, with chlorophyll). A plant takes in 211.2 g of carbon dioxide. Find the mass of glucose made and the mass of oxygen given out. (Atomic masses: H = 1 u, C = 12 u, O = 16 u)

Working: C₆H₁₂O₆ = 180 u; 6 × CO₂ = 264 u give 180 u of glucose and 192 u of oxygen

Answer: Glucose 144 g; oxygen 153.6 g

Practise Life Processes

Revise with this page, then practise: every Life Processes sheet in the app is new, with an answer key and working.

Coming soon for Android and iPhone.