1. B2 in a lesson

2. Cell Parts:

3. Bacteria Cells:

4. Yeast Cells:

5. Cells may be specialised for a particular function. Their structure will allow them to carry this function out. CellJobAdaptations Leaf cell: absorbs light for photosynthesis lots of chloroplasts Root hair cell: absorbs water and mineral ions finger like shape for large surface area Sperm cell: fertilises an egg head contains an enzyme to help penetrate egg Red blood cell: carries oxygen to the cells thin outer membrane so oxygen diffuses easily

6. Diffusion: Net movement of particles from an area of high concentration to an area of low concentration.

7. A tissue is a group of specialised cells that have a similar structure and function. cells  tissues  organs  organ systems TissueFunction Muscular tissueContracts, bringing about movement Glandular tissue Produces substances such as enzymes and hormones Epithelial tissueCovers some parts of the body

8. Organ systems are groups of organs that carry out a particular function. For example, the digestive system:

9. Leaves are adapted to absorb sunlight for photosynthesis

10. Three factors can limit the speed of photosynthesis: light intensity carbon dioxide concentration temperature

12. Glucose is produced during photosynthesis and is used by the plant to make: Cellulose - which strengthens the cell wall Proteins - such as enzymes and chlorophyll Glucose is stored by plants as starch, fats and oils. Plants also need nitrates to do this

13. The distribution of living organisms in a particular habitat may be affected by physical factors, such as: Temperature Amount of light Availability of water Availability of nutrients Availability of oxygen and carbon dioxide

14. Sampling: Quadrat Square frame Used to sample a small area Samples chosen at random

15. Sampling: Along a Transect Not random Tape stretched between two points Samples taken along the line using a quadrat Shows how the distribution of organisms changes along the line

16. Enzymes enzyme reactant + enzyme-reactant complex ↔ products enzyme + ↔ + ↔↔ + Biological catalysts: speed up reactions. Enzymes are protein molecules, and so are made up of amino acids.

17. Factors that affect enzymes: At lower temperatures rate of reaction is slow Over 40 C enzymes are denatured Active site shape is altered, therefore cannot fit substrate If pH is too far from optimum, enzyme will be denatured so active site will not fit substrate.

18. Digestive Enzymes: EnzymeMade byWorks inSubstrateProductConditions EnzymeMade byWorks inSubstrateProductConditions Amylase Salivary glands, pancreas, SI Mouth & SIStarchGlucoseNeutral EnzymeMade byWorks inSubstrateProductConditions Amylase Salivary glands, pancreas, SI Mouth & SIStarchGlucoseNeutral Protease Stomach, pancreas, SI Stomach, SI Protein Amino Acids Acid EnzymeMade byWorks inSubstrateProductConditions Amylase Salivary glands, pancreas, SI Mouth & SIStarchGlucoseNeutral Protease Stomach, pancreas, SI Stomach, SI Protein Amino Acids Acid Lipase Pancreas, SI SILipids Fatty Acids & Glycerol Neutral

19. IndustryFunction of enzymes confectionery (sweets) change glucose into fructose, which is sweeter so less is needed and is used in 'slimming' foods (isomerase). baby foodstart off digestion of food (proteases and lipases) biological detergent break down stains (proteases and lipases). What do enzymes do for us?

20. Aerobic respiration (with oxygen) glucose + oxygen → carbon dioxide + water (+ energy) When too little oxygen reaches the muscles during exercise, they use anaerobic respiration to obtain energy. An aerobic respiration (without oxygen) glucose → lactic acid (+ energy)

21. Inside each cell is a nucleus. Inside the human nucleus are 46 chromosomes (two sets of 23, one set from Mum, one set from Dad). Chromosomes are made from DNA. A section of DNA is called a gene. Where is the genetic information in a cell?

22. The genetic material is copied The cell divides once to form two genetically identical body cells Mitosis is used for growth or to replace cells. Mitosis

23. Meiosis Forms gametes (sex cells). The cell divides twice to form four gametes. Each daughter cell contains half of the chromosomes of the original cell.

24. Stem Cells Unspecialised - they can become any type of cell in the human body. As the cells of an embryo divide (by mitosis) and the embryo develops, the cells become differentiated.

25. Fossils: Evidence of early life Formed from: – Hard parts of animals that don’t decay – Parts of animals that haven’t decayed because conditions needed for decay are absent – Parts of organism are replaced by minerals – Preserved traces of organisms (footprints etc)

26. The fossil record is incomplete. Why? Early forms of life were soft bodied. Fossilisation requires very specific conditions. Many fossils are destroyed. Many fossils have not been found yet.

27. Evolution by Natural Selection Individuals in a species show a wide range of variation. This is because of differences in genes. Individuals most suited to the environment are more likely to survive and reproduce. The successful genes are then passed to the offspring in the next generation. Charles Darwin

28. Extinction What causes organisms to become extinct? Competition New predators New diseases Environmental changes

29. Why did the dinosaurs become extinct? Volcanoes Rocks formed by huge eruptions 65 million years ago can be found in India today. Meteorite Impact The remains of a 180km-wide crater caused by a meteorite 65 million years ago can be found near Mexico. Disease This theory doesn’t explain why so many sea animals died at the same time.