the-perfect-answer-revision-guide-to-biology_compress.pdf

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• Copyright © 2019 Hazel Lindsey & Martin Bailey

• Biology Edexcel IGCSE 9-1

• Revision Guide for Abdul Basit

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• Contents

1. The nature and variety of living organisms

2. Structure and functions in living organisms

3. Reproduction and inheritance

4. Ecology and the environment

5. Use of biological resources

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The Nature and Variety of Living Organisms

Characteristics of Living Organisms

• Movement

• Respiration

• Sensitivity

• Control internal conditions

• Nutrition

• Excretion

• Reproduce

• Grow

Variety of Living Organisms

• Eukaryotic: Membrane-bound organelles (e.g., animal cells).

• Prokaryotic: No membrane-bound organelles (e.g., bacteria).

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• Five Kingdoms: Plants, Animals, Fungi, Protoctists, Bacteria

• Multicellular: Organisms with many cells

• Carbohydrate Storage:

  • Animals: Glycogen

  • Plants: Starch

  • Fungi: Glycogen

• Saprotrophic Nutrition: Breaking down dead matter

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Structure and Functions in Living Organisms

Levels of Organisation

• Cell

• Tissue

• Organ

• Organ system

Main Human Organ Systems

• Reproductive

• Circulatory

• Digestive

• Gas exchange

• Nervous

• Excretory

• Endocrine

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Stem Cells

• Types:

  • Embryonic: Can differentiate into any cell type.

  • Adult: Limited differentiation.

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Biological Molecules

• Carbohydrates: Carbon, hydrogen, oxygen

• Proteins: Carbon, hydrogen, oxygen, nitrogen

• Lipids: Carbon, hydrogen, oxygen

• Test for Starch: Iodine turns blue/black

• Test for Glucose: Benedict’s solution turns brick red

• Test for Proteins: Biuret reagent turns purple

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Movement of Substances into and out of Cells

Diffusion

• Movement from high to low concentration.

• Factors affecting rate: concentration gradient, surface area, temperature.

Osmosis

• Movement of water across semi-permeable membranes.

Active Transport

• Low to high concentration (requires energy).

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Nutrition in Plants

• Photosynthesis Equation:

  • Water + CO2 (+ light) → Glucose + O2

• Limiting Factors: Light, CO2, temperature

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Nutrition in Humans

• Energy Requirement Factors: Age, pregnancy

• Digestion: Breakdown of food into soluble molecules

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• Bile: Emulsifies fats, neutralizes HCl.

• Digestion Starts: Mechanical breakdown and amylase begins carbohydrate digestion.

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Respiration

• Types: Aerobic (with oxygen) and anaerobic (without oxygen).

• Equation: Glucose + O2 → CO2 + H2O + Energy

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Gas Exchange in Plants

• Stomata: Open for gas exchange.

• Oxygen absorbed and CO2 released during photosynthesis.

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Transport Systems

Animals

• Need circulatory systems due to small surface area to volume ratio.

Plants

• Xylem: Transports water/minerals.

• Phloem: Transports sugars.

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Blood Components

• Components: Plasma, red/white blood cells, platelets

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Heart and Circulation

• Circulatory System: Heart, arteries, veins.

• Coronary Artery: Supplies oxygen to heart.

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Heart Structure

• Left ventricle thicker than right to pump blood further.

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Excretion

Plants

• Remove waste gas from respiratory processes.

Humans

• Excrete urea, CO2, sweat.

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Co-ordination and Response

Homeostasis

• Maintenance of constant internal environment.

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Nervous and Hormonal Responses

• CNS: Brain and spinal cord.

• Receptors: Sensory organs react to stimuli.

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Eye Functions

• Refraction and Pupil Control: Ciliary muscles and iris adjust focus.

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Hormones in Humans

• Insulin: Decreases blood sugar.

• Testosterone & Oestrogen: Secondary sexual characteristics.

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Reproduction and Inheritance

Sexual vs Asexual

• Sexual: 2 parents, variation.

• Asexual: 1 parent, identical clones.

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Pollination Process

• Inside Flower Anatomy: Attract insects, wind pollination.

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Female Reproductive Anatomy

• Oviduct, uterus structure & function.

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DNA and Genes

• Genotype vs Phenotype: Genetic makeup vs physical expression.

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Genetic Crosses

• Punnett Squares: Visualize inheritance.

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Pedigree Diagrams

• Show genetic conditions through generations.

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Evolution and Natural Selection

• Variability, survival, and reproduction of advantageous traits.

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Ecology and Environment

• Definitions: Environment, habitat, population and community data.

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Energy Transfer in Ecosystems

• Pyramids: Numbers and biomass significance, energy transfer.

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Human Impact

• Pollution: Effects of CFCs, greenhouse gases, acid rain on environment.

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Use of Biological Resources

• Increase yield using glasshouses and fertilizers.

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Food Production Process

• Yoghurt Making: Bacteria convert lactose.

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Genetic Modification

• Use of plasmids, insulin production in bacteria.

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Cloning

• Methods including micropropagation and adult cell cloning.