B2 Exam Revision

Plant cells vs. Animal cellsBoth types of cell have these:Only plant cells have these:NucleusThis controls the cell Cytoplasm This is the jelly like substance where chemical reaction take place

Cell wallGives support to the cell

Large vacuoleLarge space filled with cell sap

Cell membraneControls what goes in and out of the cell1)2)3)6)5)7)Mitochondria Energy is released here by respiration4) ChloroplastsWhere photosynthesis takes place

Complete this definition of Diffusion using the key words:Diffusion is the _______ __________ of ______ from where there are lots of particles ( high __________) to where there are less particles. We say the particles diffuse down a concentration _________. In cells, the cell membrane has small holes that allow small particles through, but not large molecules. We call this membrane ________ ________.The bigger the difference in concentration, the faster the rate of ________.

Partially permeableDiffusionConcentrationGradientRandom movementParticles

Osmosis is diffusion but with WATER

OSMOSIS IS THE MOVEMENT OF

WATER PARTICLES

FROM WHERE THERE ARE LOTS OF THEM (Dilute solutions)

TO WHERE THERE ARE NOT VERY MANY OF THEM (concentrated solutions)

THROUGH A SEMI-PERMEABLE MEMBRANE (LIKE A CELL WALL)OSMOSIS

Photosynthesis - The equation1. What factors are needed to make glucose?2. What products are made by photosynthesis?

Limiting factorsIf you alter the levels of light, carbon dioxide or change the temperature the rate of photosynthesis will change!

What happens to the glucose?

Mineral needsCan you fill in this table?

Mineral needs

Food chainsA food chain shows where the energy goes in a food chain (in other words, what gets eaten by what):

Pyramids of biomassIn this food chain we can see that the mass of organisms in each stage is less than in the previous stage:We can draw a Pyramid of Biomass to show this pattern:

Energy flow in a food chainConsider the energy flow in this food chain:100%10%1%0.1%Words 10%, move, sun, waste, cabbage

Improving the efficiency of a food chainClearly, food chains arent very efficient. How could the efficiency of a food chain be improved?1) Reduce the number of stages in the chain:2) Limit an animals movement or keep it warm:3) Use plant hormones to regulate the ripening of fruit

Energy in food productionBiomass and energy is lost at each stage of a food chain. The efficiency of food production can be improved by reducing the number of stages in our food chains. It would be most efficient if we all ate just plantsIf you stop animals moving around and keep them warm they lose a lot less energy which makes food production more efficient

DecayDecay is carried out by micro-organisms which work faster in warm, moist conditions with a good supply of oxygen.

The decay process releases substances that plants need to grow.

Carbon cycleThe constant cycling of carbon is known as the carbon cycleCarbon dioxide is removed from the atmosphere by photosynthesisIt is returned to the atmosphere by respiration and combustionMicrobes that decay waste and dead matter respire and produce carbon dioxide

Map from memory

EnzymesEnzymes are biological catalysts, they increase the rate of reactions.

Enzymes are protein molecules made up of long chains of amino acids.

When enzymes are denatured the active site changes shape.

What happens at the active site?In the same way that a key fits into a lock, so a substrate is thought to fit into an enzymes active site. The enzyme is the lock, and the reactant is the key.

Factors affecting enzymesIf the temperature and pH changes sufficiently beyond an enzymes optimum, the shape of the enzyme irreversibly changes. This affects the shape of the active site and means that the enzyme will no longer work.When this happens the enzyme is denatured.

Aerobic RespirationOxygen + Glucose Carbon Dioxide + Water

Energy

+ +

AmylaseProteaseLipaseBileHydrochloric acidWhere are the enzymes found?

Enzymes of digestion

HomeostasisThe internal conditions of your body need to be controlled to maintain a constant internal environmentWaste products such as carbon dioxide and urea need to be constantly removedUrea is produced by your liver as you break down excess amino acids and is removed by your kidneys as urine

Five factors we need to keep constant.1. temperature2. water3. sugar4.waste products (need to remove)5. ionsB2 Homeostasis

Use these words to complete the notes. receptors brain receptorsThe thermo-regulatory centre of the ______monitors and controls the temperature of blood as it passes through.This centre has __________which are sensitive to the temperature of the blood.The skin also has _________ sensitive to temperature.B2 Homeostasis

Glucose controlYour blood glucose concentration is monitored and controlled by your pancreasInsulin and glucagon are the hormones involved in controlling blood sugar. Insulin converts glucose to glycogen and glucagon converts glycogen to glucoseIn diabetes the blood glucose may rise to fatally high levels because the pancreas does not produce enough insulin. It can be controlled by injections and diet

Chromosomes, Genes and Alleles1. ..2. .......3. ..4. Bb5. .Nucleus, Gene, Chromosome, Allele, Cell(b)

Gregor Mendel (The Pea Plant Man)Why was his work not spread quickly?He was not a famous scientist nobody knew about him at the time.His job as abbot stopped him giving lectures at universities.He published his work in an obscure journal that few people read.Biologists at the time did not think mathematics had anything to do with Biology.

Disease Some disorders are inheritedHuntingtons disease is caused by a dominant allele of a gene and can be inherited from only one parentCystic fibrosis is caused by a recessive allele of a gene and so must be inherited from both parents

Cystic FibrosisThe treatment involves chest physiotherapy.They are very prone to chest infections and malnutrition.The mucus encourages the growth of pathogenic microbes that cause infection and cause long term lung damage.

PHEW!Good Luck

*Boardworks GCSE Additional Science: Biology Enzymes*Boardworks GCSE Additional Science: Biology EnzymesTeacher notesThis activity could be used to check students understanding of chemical digestion.