Biology 2 warm up session

1. Biology 2 warm up session

2. Animal Cells • Nucleus - controls cell’s activities • Cytoplasm - where chemical reactionstake place • Cell membrane- controlswhat enters and leaves cell • Mitochondria - where energy is releasedduring aerobicrespiration • Ribosomes - where proteins are made

3. Plant Cells Plant cells also have: • A rigidcell wall- for strength and support (made from cellulose) • Chloroplasts - absorb lightto make energy for photosynthesis • Vacuole filled with cell sap

4. 1. Guard cell – can open and close to control exchange of gases and water loss 2. Sperm cell – long tail providing movement s it can swim to and fertilise egg. Nucleus contains genetic material 3. Red blood cell – concave disc shape - increases area to carry more oxygen 4. Egg cell (ovum) – large – maximum exposure for sperm, has a large food store 6. White blood cell – can change shape to digest microbes 7. Neurone – long like wires to carry messages around the body 5. Root hair cell – large surface area to absorb water and minerals. Thin cell wall so minerals can pass through easily. Positioned close to xylem tissue.

5. Cells, tissues and organs Cells, tissues and organs

6. Plant tissue Example of plant tissues include: • Epidermal tissue, which cover the plant • Mesophyll, which carries out photosynthesis • Xylem and phloem, which transportsubstances around the plant

7. Types of animal tissue ..... A tissue is a group of cells with similar structure and function. Examples of tissue include: • Muscular tissue, which can contract to bring about movement • Glandular tissue, which can produce substances such as enzymes and hormones • Epithelial tissue, which covers some parts of the body

8. Organs Organs are made of tissue. One organ may contain several tissues. The stomach is an organ that contains: • Muscular tissue, to churn the contents • Glandular tissue, to produce digestive juices • Epithelial tissue, to cover the outside and inside of the stomach

10. Osmosis is the: • diffusion of water from a • dilute to a more concentrated solution • through a partially permeable membrane

11. Quantitative data on the distribution of organisms can be obtained by: Randomsampling Samplingalong a transect • To sample along a transect: • Choose area to sample • Choose a straight line through the area • Place quadrat at one end of the line • Count number of species within quadrat • Repeat at 5 set intervals along the line • To sample randomly: • Choose area to sample • Place quadrat randomly onto area • Count number of species within quadrat • Repeat 5 times

12. Photosynthesis Carbon dioxide + water (+ light energy)  Glucose + Oxygen • Photosynthesis is when green plants use light energy to make their own food. The rate of photosynthesismay be limited by 3 things: • 1) carbon dioxide • 2) light intensity • 3) temperature

13. Limiting carbon dioxide levels • Increasing carbon dioxide levelsincreases the rate of photosynthesisup to a point. • Eventually one of the other factors (temperature and light) becomes limiting • If there is too little carbon dioxide the rate will slow down.

14. Limiting light intensity • Increasing light intensity increases the rate of photosynthesis up to a point • When a certain light intensityis reached the rate of photosynthesis stays constant • Eventually one of the other factors becomes limiting

15. Limiting temperature • If it is cold then enzymes do not work effectively slowing down the rate. • The rate of photosynthesis increases steadily with a rise in temperature up to a certain point (35-40ºC = optimum temp) • After this the enzymes are destroyed/denatured and the reaction stops completely.

17. heat pH normal denatured Enzymes and their structure • Enzymes are: • Biological catalysts –speed up reactions in living things • Protein molecules - made up of amino acids • The shape of the enzyme (active site) is vital to its function. • 1.) High temperaturesdestroyenzymes ‘special shape’ so it becomes denatured. • 2.) Different enzymes work best at different pH values.

18. Structure of proteins • Proteins molecules are made up of long chains of amino acids • These long chains are folded to produce a specific shape that enables other molecules to fit into the protein

19. Enzymes in digestion

20. Enzymes in digestion

21. Enzymes in digestion • Also: • 1.) Hydrochloric acid – in the stomach creates acidic conditions (low pH) because enzymes in the stomachwork best in acidic conditions • 2.) Bile • produced in the liver • stored in the gall bladderbefore being released into the small intestine. • Bile neutralises the acidthat was added to food in the stomach. • This provides alkaline conditionsin which enzymes in the small intestine work bestat.

22. Making use of enzymes

23. Enzymes in industry

24. What is aerobic respiration? + + +  glucose oxygen carbon dioxide water energy Aerobic respiration can be summarized by this equation: Mitochondria are the energy-producing part of the cell. • The energy that is released during respiration is used for: • GROWTH • MOVEMENT • HOMEOSTASIS (maintaining constant temp in mammals and birds) • making PROTEINS

25. Anaerobic respiration Anaerobic respiration is the incomplete breakdown of glucose and produces lactic acid. As the breakdown of glucose is incomplete, much less energy is released than during aerobic respiration.

26. Inside the nucleus

27. Mitosis • Mitosis is the division of body cells • Produces new identical cellsfor growth and repair • Before cell division, geneticinformationon the chromosomes is copiedso new cells have the same genes as the parent cells – each cell has 23 pairs/46 chromosomes

28. Meiosis • MEIOSIS is : • Cells in reproductive organs divide to form sex cells – sperm and egg cells (gametes) – contain 23 chromosomes • The cell now divides twice to form 4 gametes

29. What are stem cells? The first cells are stem cells. These are unspecialized cells capable of developing into many different types of cell. Stem cells found in embryos are called embryonic stem cells and develop into all the different types of cell in the body. If stem cells continued to divide as they were, humans would end up as a large jelly-like blob!

30. Changing cells When the embryo contains about 500 cells, the cells stop being the same and they stop getting smaller with each division. They start to differentiate into different types of cell. At this point, stem cells no longer form two new stem cells when they divide. Instead, one of the two daughter cells becomes a progeny or tissue cell. stem cell stem cell tissue cell

31. cardiac muscle red bloodcells nerve cells cells Becoming specialized Tissue cells continue to divide and differentiate, each time becoming more and more specialized. stem cell tissue cells Some will become nerve cells, others will become blood cells, muscle cells, bone cells, etc.

32. A controversial source? Most stem cell research has used cells obtained from embryos left over from fertility treatment. These are called embryonic stem cells (ESCs) and are the most powerful type because they can turn into any type of cell. Their use in research is strongly criticized by people who believe it is unethical to kill embryos for their cells. Stem cells from fetuses are almost as powerful, and these have also been found in the blood of umbilical cords and amniotic fluid of pregnant women.

33. What are adult stem cells? Adults also contain stem cells, where they are found in small numbers in many organs, including bone marrow, brain, skin and muscle. Adult stem cells normally maintain and repair damaged tissue, and can usually only make a small number of cell types. For example, adult stem cells in the skin only normally form skin cells. Research has shown that some adult stem cells can be manipulated to produce many different cell types (e.g. brain stem cells can make muscle cells). This is called plasticity.

34. ? allele forbrown eyes allele forblue eyes Alleles • Some characteristics are controlled by a single gene. • Different forms of genes are called alleles • Eg, for eye colour, skin colour, hair colour etc

35. Genetic diagrams/Punnet squares Eg, the allele for brown eyes (B) is dominant to the allele for blue eyes (b) If 2 parents have brown eyes and have the genetic make up Bb, what would be the chance of them having a blue-eyed child? 75% chance brown eyed child 25% blue eyed child

36. Polydactyly Polydactyly – having extra fingers or toes – is caused by a dominant allele of a gene and can therefore be passed on by only one parent who has the disorder

37. Inherited disorders Huntington’s disease • A disorder of the nervous system • Caused by dominant alleleof a gene • Can be passed on by only one parentwho has the disorder • 50% chance of inheriting disease

38. Inherited disorders Cystic fibrosis • A disorder which affects cell membranesin many organs of the body particularly the lungs and the pancreas • Caused by recessive alleleso must be inherited by both parents

39. Gregor Johann Mendel

40. What causes extinction? • Disease • New predators • Climate or environment change • New competitors

41. Some final tips... • Read the whole Q – 33% of the Qs can be answered from information given to you in text, diagrams, graphs & tables • Follow instructions – “tick one box” “tick two boxes” “use info from the table” • Don’t write “it” – “the concentration increases” NOT “it increases” • What is the Q asking you to do?

42. Don’t forget...

43. Things to think about when evaluating a situation... • Economical aspect - money • Environmental – pollution, greenhouse gases, global warming, acid rain, carbon dioxide? • Health risks – body rejection/damage • Availability/accessibility • Ethical • Religious

44. Remember... • 1 mark per minute – you have 60 minutes to answer 60 marks • Use bullet points – 3 marks should mean 3 bullet points

45. Good luck 