Biology 2 warm up session: Higher tier

Remember, you have learnt all the information on the following slides in your lessons. This is just to refresh your memory of the essentials

Animal Cells Nucleus - controls cell’s activities Cytoplasm - where chemical reactions take place Cell membrane - controls what enters and leaves cell Mitochondria - where energy is released during aerobic respiration Ribosomes - where proteins are made

Plant Cells Plant cells also have: A rigid cell wall - for strength and support Chloroplasts - absorb light to make energy for photosynthesis Vacuole filled with cell sap

These are cells adapted to carry out different functions Specialised cells These are cells adapted to carry out different functions

Different types of cells Yeast cells have a nucleus, cytoplasm and a membrane surrounded by a cell wall A bacterial cell have a cytoplasm, cell membrane and a cell wall But the genes are not in a distinct nucleus

Diffusion and concentration gradients high concentration low Diffusion is the spreading of the particles… …from a higher concentration to a region of lower concentration... …the greater the difference in concentration, the faster the rate of diffusion. Diffusion happens in gas exchange in the lungs and in leaves

Enzymes and their structure normal denatured heat pH Enzymes are biological catalysts –they speed up reactions in living things Enzymes are protein molecules - made up of amino acids The shape of the enzyme is vital to its function. Temperature and pH affect enzyme activity 1.) High temperatures can destroy the enzymes ‘special shape’ so it becomes denatured. 2.) Different enzymes work best at different pH values.

Enzymes in digestion Enzyme: Produced in Job Where Amylase - Salivary glands - Pancreas - Small intestine Catalyses the breakdown of starch into sugars Mouth Small intestine Protease Stomach Pancreas Catalyses the breakdown of proteins into amino acids Lipase Catalyses the breakdown of lipids (fats and oils) into fatty acids and glycerol

Making use of enzymes

Enzymes in industry Type of enzyme Proteases Carbohydrases Isomerases Use To ‘pre-digest’ protein in baby foods To turn starch into sugar syrup for making chocolates and cakes To turn glucose syrup into fructose syrup to use in slimming foods Why is it used? The baby may not be able to digest all the protein itself Sugar syrup is sweet and makes the food ‘taste nice’ Fructose is twice as sweet as glucose so it can be used in smaller amounts in slimming foods

Body organisation The body is made of cells A group of cells that work together are called a tissue A group of tissues that work together are called an organ A group of organs that work together are called an organ system

Types of animal tissue A tissue is a group of cells with similar structure and function. There are 3 examples of tissue: 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

Types of plant tissue include Palisade layer – where photosynthesis happens Spongy mesophyll layer – allows gases to reach palisade layer Xylem – transports water and nutrients Phloem – transports food (e.g. sugars) Xylem and Phloem

The digestive system includes

Aerobic respiration can be summarized by this equation:  + oxygen carbon dioxide water glucose energy Mitochondria are the energy-producing part of the cell. The energy that is released during respiration is used: For GROWTH MOVEMENT MAINTAINING A CONSTANT TEMPERATURE (in mammals and birds) MAKING PROTEINS Teacher notes See the ‘Animal and Plant Cells’ presentation for more information about mitochondria and respiration.

Aerobic respiration during exercise During exercise the heart rate increases and the rate and depth of breathing increases... …this increases the supply of sugar and oxygen to cells and increases the rate of removal of carbon dioxide Circulation

Anaerobic respiration During exercise, if insufficient oxygen is reaching the muscles they use anaerobic respiration to obtain energy. 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.

Inheritance recap – Inside the cell

Mitosis Mitosis is the division of body cells Produces new identical cells for growth and repair Before cell division, genetic information on the chromosomes is copied so new cells have the same genes as the parent cells

Meiosis (Higher) Cells in reproductive organs (testes and ovaries) divide to form sex cells (gametes) Before division a copy of each chromosome is made. The cell now divides twice to form 4 gametes – each new cell has half a set of chromosomes Sexual reproduction results in variation as the new individual gets half a set of chromosomes from each parent

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

Inherited disorders Polydactyly A disorder causing extra fingers or toes Caused by dominant allele of a gene Can be passed on by only one parent who has the disorder 50% chance of inheriting disease

Inherited disorders Cystic fibrosis A disorder which affects cell membranes in many organs of the body particularly the lungs and the pancreas Caused by recessive allele so must be inherited by both parents

Embryo screening Unborn embryos can be checked for the alleles that cause these and other genetic disorders… …some people think this leads to more abortions and so they think it’s unethical

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

Limiting carbon dioxide levels Increasing carbon dioxide levels increases the rate of photosynthesis up 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. Carbon dioxide maybe limited in an enclosed space eg, a greenhouse on a sunny day or in a rapidly photosynthesising rain forest

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

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 and the reaction stops completely.

Healthy plant growth Stunted growth Yellow leaves Plant roots absorb mineral ions needed for healthy growth For healthy growth plants need mineral ions including Nitrates and Magnesium Mineral ions: Nitrates Magnesium Needed for: Nitrates used to make proteins for growth Needed for chlorophyll production Symptoms shown by plants if deficient in mineral Stunted growth Yellow leaves

Populations The factors that effect population size are: Temperature Availability of nutrients Amount of light Availability of water Availability of oxygen and carbon dioxide Limits of Population

There are 2 methods for collecting environmental data To sample randomly: Choose area to sample Place quadrat randomly onto area Count number of species within quadrat Repeat 5 times To sample along a transect: Choose a straight line through the area Place quadrat at one end of the line Repeat at 5 set intervals along the line

Fossils and exctinction Fossils are the remains of dead plants and animals which lived millions of years ago. Fossils show us how much or how little different organisms have changed as life developed on Earth. Many early life forms were soft-bodied... which means that they have left few traces behind....what traces there were have been mainly destroyed by geological activity.

Fossils and exctinction Extinction may be caused by: - changes to the environment - new predators, diseases or more successful competitors - a single catastrophic event, eg massive volcanic eruptions or collisions with asteroids

Fossils and exctinction New species arise as a result of: isolation – two populations of a species become separated, eg geographically HT only: genetic variation – each population has a wide range of alleles that control their characteristics natural selection – in each population, the alleles that control the characteristics which help the organism to survive are selected speciation – the populations become so different that successful interbreeding is no longer possible.

Some scientific terms... Reproducible Would another scientist be able to repeat it and get the same results? Valid Keep everything the same except the independent & dependent variables Precision Smaller scale division on equipment Range From the smallest to biggest Interval What the values go up by Claims You decide if it is true or false by looking at evidence, independent organisations avoid bias

What is the questions asking you to do? Describe a graph Refer to the pattern e.g. as……...increases………increases etc Explain Describe & give a reason “because…….” Evaluate For & against Compare What is the same & what is different Calculate Show calculations & give units Suggest a reason This should be scientific

Things to think about when evaluating a situation... Economical aspect - money Environmental – pollution/ greenhouse gases/ global warming/ acid rain/ carbon dioxide/ habitat destruction Health risks – body rejection/damage Availability/accessibility Ethical – suffering/human rights Religious

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 a box” “tick two boxes” “use info from the table” Don’t write “it” – “the concentration increases” NOT “it increases”

And remember... 1 mark per minute – you have 60 minutes to answer 60 marks Use bullet points for short questions – e.g. 3 marks should mean 3 bullet points Write in ‘good English’ for the 6 mark question Check your answers – read over your answers at the end

Good luck 