Edexcel GCSE Biology Paper 2 Overview

Topics Covered

• Topic 6: Plants
• Topic 7: Coordination, Control, and Homeostasis
• Topic 8: Exchange and Transport
• Topic 9: Ecosystems

Plants

• Organs: Leaves (photosynthesis), Roots (water and mineral ions intake), Xylem (water transport), and Phloem (sugar transport).

• Transpiration: Water movement through plants; increases with higher temperature, lower humidity, and more air movement.

• Leaf Structure:

  • Waxy cuticle: Prevents water loss.
  • Upper epidermis: Transparent, allows light for photosynthesis.
  • Palisade mesophyll: Chloroplast-rich for photosynthesis.
  • Spongy mesophyll: Air spaces for gas exchange.
  • Vascular bundle: Contains xylem and phloem.
  • Lower epidermis: Contains stomata for gas exchange.

• Photosynthesis:

  • Location: Chloroplasts.
  • Endothermic reaction needing light.
  • Uses of glucose: respiration, conversion to starch/fat, cellulose, amino acids.
  • Limiting factors: Temperature, light intensity, CO2 concentration.

• Plant Hormones:

  • Gibberellins: Seed germination.
  • Ethene: Fruit ripening.
  • Auxins: Growth direction, phototropism and geotropism.

Coordination, Control, and Homeostasis

• Homeostasis: Regulation of internal conditions.

  • Examples: Thermoregulation, blood glucose levels.

• Endocrine System:

  • Slow, uses hormones via blood.
  • Key glands: Pituitary ("master gland"), pancreas (insulin production), adrenal (adrenaline production).

• Blood Glucose Regulation:

  • Insulin: Lowers blood glucose.
  • Glucagon: Raises blood glucose.
  • Diabetes: Type 1 (lack of insulin), Type 2 (cell resistance to insulin).

• Water and Nitrogen Balance:

  • Kidneys regulate water via ADH.
  • Nitrogen waste (urea) produced by protein breakdown.

• Reproduction:

  • Menstrual cycle hormones: FSH, LH, estrogen, progesterone.
  • Contraception methods: Pills, injections, condoms, IUDs.
  • Fertility treatments: IVF.

Exchange and Transport

• Circulatory System:

  • Double circulation: Pulmonary and systemic circuits.
  • Heart structure: Right/left atrium and ventricles, pacemaker cells.
  • Blood vessels: Arteries, veins, capillaries.

• Respiratory System:

  • Gas exchange: Trachea, bronchi, bronchioles, alveoli.
  • Oxygen transport by hemoglobin, CO2 exhalation.

• Respiration:

  • Aerobic: With oxygen.
  • Anaerobic: Without oxygen, produces lactic acid.

Ecosystems

• Food Chains and Trophic Levels:

  • Producers, consumers (primary, secondary, tertiary), apex predators.

• Carbon and Nitrogen Cycles:

  • Carbon recycled via decomposition.
  • Nitrogen converted by bacteria.

• Environmental Issues:

  • Pollution, loss of biodiversity, waste management.

• Food Security:

  • Challenges: Population growth, changing diets, climate change.
  • Sustainable practices: Fishing methods, reducing biomass loss.

• Additional Tools: Quadrats for population estimation, transects for distribution changes.

Note: This overview is meant to condense major topics and themes for Edexcel GCSE Biology Paper 2. It spans both higher and foundation tiers, with some content exclusive to the triple science course.