Biology Unit 2

Unit 2

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  • Created by: Chloe
  • Created on: 11-04-11 19:57


  • The structure of cells is related to their function
  • Cells may be specialised to carry out a particular job
  • Animal and plant cells have a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes
  • Plant cells also have a cell wall, chloroplasts and a permanent vacuole
  • Diffusion=Movement of Particles from high to low concentration
  • Osmosis=Movement of water from high to low concentration
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Plant growth

  • Green plants make their own food using sunlight. This process is called photosynthesis


Word equation: Carbon dioxide + Water ---------------> Glucose + Oxygen


  • Rate of photosynthesis is limited by temperature, carbon dioxide concentration and light intensity
  • Plants need to absorb mineral ions (nitrates and magnesium) for healthy growth
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Food chains and Biomass

  • A Food chain represents the transfer of energy from organism to organism
  • Pyramids of biomass show the mass of living materials at each stage of the food chain. Biomass is lost at each stage


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Recycling materials

  • Living things remove materials from the environment.
  • These materials are returned to the environment when the organisms die or excrete waste
  • the carbon cycle is the constant recycling of carbon material
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Aerobic respiration

Aerobic Respiration takes place using oxygen.


Glucose + Oxygen ---------------------> Carbon Dioxide + Water (+ energy) 

                                   by enzymes

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  • Enzymes are biological catalysts
  • Inside body cells enzymes speed up reactions such as respiration, protein synthesis and photosynthesis
  • Outside body cells, digestive enzymes are produced int he digestive system
  • Bile, produced in the liver, neutralises acids and emulsifies fats

Amylase: produced in the Salivary glands, Pancreas and Small intestine

Protease: produced in the Stomach and Small intestine

Lipase: produced in the Pancreas and Small intestine

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Controlling body conditions

  • The human body has to control the levels of blood sugar, water, ion and temperature
  • Diabetes= A condition in which the pancreas isn't able to control the levels if insulin in the body
  • Body temperature is monitored and controlled by the thermoregulatory centre in the brain

If the body temperature is too high then the blood vessels will dilate and the sweat glands will release sweat

If the body temperature is too low then the blood vessels will constrict adn teh muscles will start to shiver causing heat energy to be released

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Human Body cells

  • Human body cells----->46 Chromosomes---->23 pairs
  • Gametes----->sex cells----->23 chromosomes
  • Two gametes join together to produce a zygote with 46 chromosomes
  • DNA----->Gene----->Chromosome
  • Alleles=create variation of genes
  • Dominant Alleles- control gene characteristics if present once
  • Recessive alleles- only control gene characteristics if present twice
  • Differentiation- cells carry out specific function
  • Stem cells have not yet differentiated
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  • Mitosis=Division of body cells to produce new cell
  • The new cells contain identical genetic information to that of the parent cell
  • After fertilisation, a zygote divides repeatedly by mitosis to form a new individual
  • Meiosis= Division of cells in the testes and ovaries to produce gametes
  • The gametes will have half the number of chromosomes as the parent cell
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Danae Josephine


Good job, basic points.. easy to learn from (:


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