Edexcel A level biology Study guides, Class notes & Summaries

What type of reactions do organisms need to carry out to survive? - Answer Metabloic Reactions What is a catalyst? - Answer A chemical that speeds up the rate of reaction and remains unchanged and reusable at the end of the reaction What are biological catalysts for metabolic reactions? - Answer enzymes any molecule that can have a reaction catalaysed by an enzyme is called a ... - Answer Substrate What is an enzymes turn-over number? - Answer The number of substrates an en...

4.1: Explain how the variety of species has generally increased over time. - Answer Variety of life has become more extensive because species adapted to all environments in the world- even extreme habitats. 4.2: Explain the negative impact that some human activities (give 3 examples) have on diversity of species. - Answer -Deforestation/loss of habitat leads to decrease in species richness -Whole ecosystems are affected when species rapidly decline -Leading to extinction or imbalance in...

It's dipolar so it's a good solvent. And it has strong hydrogen bonds therefore it's cohesive - Answer Why is water good for transport? Gas exchange doesn't happen efficiently through diffusion so substances need to be transported around the body to organs - Answer Why do multicellular organisms need a mass transport system? Atrium systole - Answer What is it called when the atrium contracts and the AV valves open? Ventricle systole - Answer What is it called when the AV val...

1. Investigate the effect of caffeine on heart rate of Daphnia - Topic 1 - Answer Daphnia of same species Placed on microscopic tray in pond water in bits of cotton and allowed to acclimatise for 5 minutes Then BPM counted using tally marks of a sheet of paper for 15 seconds, x4 to give BPM repeated with unknown conc. of caffeine (blind) 0.0% and distilled water, 0.1% and 0.5% Repeat with each daphnia and with other daphnia calculate mean 2. Investigate the vitamin C content of food ...

What is standard deviation? -Answer a computed measure of how much scores vary around the mean score What is a serial dilution? -Answer used to obtain a series of solution whose concentrations differ by known amounts Why do we measure initial rate of reaction? -Answer Reaction can be controlled, as when reaction starts substrate concentration will decrease fast What does catalase catalyse? -Answer break down of hydrogen peroxide to water and oxygen gas What does coppe...

Add/Label - Answer Requires the addition or labelling to a stimulus material given in the question, for example labelling a diagram or adding units to a table. Assess - Answer Give careful consideration to all the factors or events that apply and identify which are the most important or relevant. Make a judgement, come to a conclusion. Calculate - Answer Obtain a numerical answer showing the relevant stages in the working. Don't forget the units. Comment on - Answer Form a judg...

What does CFTR protein mean? - Answer Cystic Fibrosis Transmembrane Concordance Regulator (gated channel protein) What does ENaC stand for? - Answer Epithelial Sodium Ion Channel What happens if there is excess water in an unaffected person's airways? - Answer 1) Excess water detected by the epithelial cell membrane 2) Carrier proteins in the basal membrane actively pump sodium ions out of the cell into the tissue fluid 3) Sodium ions diffuse from the mucus, down the gradient by f...

Cell theory - Answer States that new cells are formed from existing cells and that the cell is a fundamental unit of structure, function and organisation in all living organisms. it is considered a unifying concept in biology Cells, tissues and organs - Answer In complex organisms, cell are organised into tissues, tissues into organs, organs into systems e.g. animal↓ muscle cell → muscle → heart → circulatory system specialised cell → tissue → organ → system xylem vesse...

What are carbohydrates made out of? - Answer carbon, hydrogen and oxygen What is a monosaccharide (with examples of 3)? - Answer Carbohydrates with a single sugar unit, such a glucose, fructose and ribose What is a disaccharide (with 3 examples)? - Answer A carbohydrate with two sugar units, including maltose, sucrose or lactose. What is a true polysaccharide (with three examples)? - Answer A long chain of sugars that has been made through condensation polymerisation, these ...

Structure and function of plasmids. - Answer - Small short lengthed loops of DNA - contains genes for uses like antibiotic resistance Structure and function of the flagella / flagellum. - Answer - Hollow cylindrical long hair like structures. -This rotates to make prokaryotic cells move. Structure and function of the slime capsule. - Answer - Thick gel like substance -- Protection and prevents dehydration Structure and function of the pili. - Answer - Short hair like structur...