Biology Notes for IGCSE 2014
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    • All Notes
    • 01 Classification
    • 02 Cells
    • 03 Enzymes
    • 04 Plant Nutrition
    • 05 Animal Nutrition
    • 06 Plant transport
    • 07 Human transport
    • 08 Respiration
    • 09 Coordination
    • 10 Excretion
    • 11 Homeostasis
    • 12 Reproduction
    • 13 Inheritance
    • 14 Ecosystem
  • Classification
    • Summary
    • Characteristics of Living organisms
    • Classification of Living organisms
    • Kingdoms of Living organisms
    • Animal Kingdom >
      • Classification
      • Phylum Vetebrates
      • Phylum Arthropods
      • Annelids, Nematodes, Molluscs
    • Plant Kingdom
    • Virus
    • Bacteria Kingdom
    • Fungi Kingdom
    • Dichotomous keys
  • Cells
    • Summary
    • Structure
    • Functions
    • Tissues, Organs, Systems
    • Diffusion
    • Osmosis
    • Active transport
  • Enzymes
    • Summary
    • Enzymes and reactions
    • 'Lock and Key' model
    • Role in germinating seeds
    • Use in biological washing powders
    • Use in the food industry
    • Use of microorganisms and fermenter to manufacture enzymes
    • Use of microorganisms to manufacture antibiotic penicillin
  • Nutrition
    • Animal >
      • Summary
      • 1 >
        • Main nutrients: carbohydrates, fats and proteins
        • Food tests >
          • Food test 1 - Starch test
          • Food test 2 - Benedict's test for Reducing Sugars
          • Food test 3 - Emulsion (ethanol) test for Fats
          • Food test 4 - Biuret test for Proteins
        • Other Nutrients: Vitamins, Minerals, Fiber and Water
        • Using yeast to make bread and beer
        • Using microorganism in making yoghurt and single cell protein
        • Food additives - uses, benefits and health hazards
        • Use of modern technology for increasing food production
      • 2 >
        • Problems of world food supplies and the causes of famine
        • Diet
        • Human alimentary canal
        • Human teeth and dental decay
        • Adding fluoride to public water supplies
        • Mechanical and chemical digestion
        • Absorption – function of the small intestine and significance of villi
        • Assimilation and role of the liver
    • Plant >
      • Summary
      • The equation for photosynthesis
      • Photosynthesis investigations - Principles and Starch test
      • Effect of Light intensity on the rate of Photosynthesis
      • Effect of Temperature on the Rate of Photosynthesis
      • Effect of Carbon Dioxide on the Rate of Photosynthesis
      • Limiting factors in photosynthesis
      • Optimum conditions for photosynthesis in Green house
      • Leaf structure
      • Plant's mineral requirements and fertilisers
  • Transport
    • Plant >
      • Summary
      • Functions of xylem and phloem
      • Distribution of Xylem and Phloem in roots, stems and leaves
      • Root hairs and water uptake by plants
      • Passage of water through root, stem and leaf
      • Transpiration in plants and factors affecting tranpiration rate
      • Adaptations of the leaf, stem and root to different environments
      • Translocation of organic foods in plants
      • Translocation of applied chemicals throughout the plant
      • Transport of materials from sources to sinks at different seasons
    • Human >
      • Summary
      • 1 >
        • The circulatory system
        • Structure and function of the heart
        • Effect of exercise on heartbeat and causes of a coronary heart disease
        • Arteries, veins and capillaries - structure and functions
        • Blood composition and Plasma
        • Blood cells - structure and functions
      • 2 >
        • Blood clotting
        • Immune system - antibody, tissue rejection
        • Functions of lymphatic system
        • Respiration
        • Aerobic and anaerobic respiration
        • Gaseous exchange
  • Respiration
    • Summary
    • Definition
    • Aerobic, anaerobic
    • Gaseous exchange
    • Inspired, expired air
    • Tobacco smoke
  • Reproduction
    • Summary
    • Types
    • Plant >
      • Pollination
      • Flower structure
      • Formation of seed
      • Seed dispersal
      • Self-pollination, cross-pollination
      • Growth and development
    • Human >
      • Reproductive system
      • Menstrual cycle
      • Fertilisation
      • Fetus development
      • Birth
      • Sex hormones
      • Birth control
      • Artificial insemination
      • HIV/AIDS
      • Gonorrhoea
      • Breast feeding
  • Coordination
    • Coordination >
      • Summary
      • Hormones, adrenaline
      • Hormones in food production
      • Human nervous system
      • Simple reflex arc
      • Effectors, biceps and triceps
      • Voluntary, involuntary actions
      • The eye, rods and cones
      • Accommodation
      • Tropism in plants
      • Auxins
    • Homeostasis >
      • Summary
      • Homeostasis
      • Blood glucose
      • Negative feedback
      • Kidney structure
      • Kidney function
      • Formation of urea
      • Dialysis
      • Drugs
  • Inheritance
    • Summary
    • Key definitions
    • Chromosomes, DNA
    • Mitosis and Meiosis
    • Monohybrid cross
    • Codominance
    • Continuous, discontinous
    • Mutation, radiation
    • Sickle cell anaemia
    • Selection
    • Antibiotic-resistance bacteria
    • Genetic engineering
  • Ecosystem
    • Summary
    • Human & ecosystem >
      • Human influences
      • Deforestation
      • Water pollution
      • Air pollution
      • Greenhouse gases
      • Pesticides, nuclear fallout
      • Conservation, recycling sewage
    • Energy flow
    • Food chain
    • Food web
    • Food pyramids
    • Energy efficiency
    • Carbon & water cycles
    • Nitrogen cycle
    • Combustion of fossil fuels
    • Population size

 #81. Reproduction in plants - agents of pollination

Reproduction in flowering plants may occur both sexually or asexually.
Pollination can take place with the help of agents : wind or insects
These flowers then produce seeds which can be dispersed by either the wind or other animals.
Picture
Pollination:  transfer of pollen grains from the male part of the plant (anther) to the female part (stigma).  
Picture
Pollen grains.
Structural adaptations
Picture
Common misconceptions

Students often get confused between pollination and seed dispersal. When animals such as insects carry pollen, they aid pollination. When animal carry seeds, they aid seed dispersal. 

Growth of pollen tube and the process of fertilization

Figure below shows a section through a single carpel. 
Picture
If pollen grains are of the same species as the flower they land on, they may germinate. Germination is triggered by a sugary solution on the stigma, an involves the growth of a pollen tube from the pollen grain. 

The pollen tube contains the male nucleus, which is needed to fertilise the ovule inside the ovary. The pollen tube grows down the style, through the ovary wall, and through the micropyle of the ovule. 

Fertilisation is the fusion of the male nucleus with the female nucleus. If the ovary contains a lot of ovules, each will need to be fertilised by a different pollen nucleus.

Video: Flower Reproduction

Video: Sexual Reproduction in Flowering Plants 

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