Aqa a level biology 4 Study guides, Class notes & Summaries

AQA A Level Biology

A marked A* example of an AQA A-level Biology essay in paper 3, containing 4 paragraphs and a mind-map essay plan on the importance of membranes in living organisms. This essay is synoptic, detailed, coherent and links back to the question, which scored 20+ marks.

AQA A-level Biology - Topic 4 Questions and Answers 100% Solved Define variation Differences that exist between individuals In what ways can variation be caused? It can be caused by genetic factors, such as alleles from mutations. It can also be caused by the environment, such as climate. Most variation is caused by a combination of genetic factors and environmental factors Why is it impossible to study a whole population? Because it is too large and would take too long. Instead, scient...

AQA A-level Biology - Topic 4 Questions and Answers 100% Solved Define variation Differences that exist between individuals In what ways can variation be caused? It can be caused by genetic factors, such as alleles from mutations. It can also be caused by the environment, such as climate. Most variation is caused by a combination of genetic factors and environmental factors Why is it impossible to study a whole population? Because it is too large and would take too long. Instead, scient...

AQA A-level Biology - Topic 4 Already Passed Define variation Differences that exist between individuals In what ways can variation be caused? It can be caused by genetic factors, such as alleles from mutations. It can also be caused by the environment, such as climate. Most variation is caused by a combination of genetic factors and environmental factors Why is it impossible to study a whole population? Because it is too large and would take too long. Instead, scientists use a sample th...

AQA A LEVEL BIOLOGY PAPER 1 2021. Describe the induced-fit model based on enzyme action and how an enzyme acts as a catalyst. [3 marks] . 2 Scientists investigated the action based on the enzyme ATP synthase. They made reaction mixtures each containing: • ATP synthase • buffer (to control pH) • substrates. One based on the substrates required within these reaction mixtures is inorganic phosphate (Pi). Tick ( ) one box to show which other substrate the scientists must add to the ...

AQA A-level Biology - Topic 4 Exam – Questions & Answers

AQA A-level BIOLOGY 7402/2 Paper 2 Mark scheme June 2022 Version: 1.0 Final. MARK SCHEME – A-LEVEL BIOLOGY – 7402/2 – JUNE 2022 2 Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant questions, by a panel of subject teachers. This mark scheme includes any amendments made at the standardisation events which all associates participate in and is the scheme which was used by them in this examination. The standardisation process ensures that th...

AQA A-level BIOLOGY 7402/3 Paper 3 Mark scheme June 2023 (VERIFIED) (There are) stretch-mediated sodium ion channels (in the membrane); 2. (Increased pressure) deforms/changes (sensory neurone/axon) membrane/lamella(e) OR (Increased pressure) deforms/changes sodium ion channels; 3. Sodium ion channels open; 4. Sodium ions diffuse in; 5. Depolarisation (leading to generator potential); 3 max (3 x AO1) 1. 2. 3. or 4. Accept Na+ Max 2 if only reference to sodium and not sodium ions...

Many different substances enter and leave a cell by crossing its cell surface membrane. Describe how substances can cross a cell surface membrane. (5) 1 (Simple / facilitated) diffusion from high to low concentration / down concentration gradient; 2 Small / non-polar / lipid-soluble molecules pass via phospholipids / bilayer; OR Large / polar / water-soluble molecules go through proteins; 3 Water moves by osmosis / from high water potential to low water potential / from less to more nega...