Aqa a level biology cells - Study guides, Class notes & Summaries

AQA A-Level Biology - Topic 3 Questions and Answers 100% Solved Smaller organisms have a ........... surface area to volume ratio Higher How do single called organisms exchange substances? Diffuse directly into or out of the cell across the cell surface membrane Give 2 reasons why in multicellular organisms, diffusion across outer membrane would be too slow? 1. Some cells deep within body- big distance between them and outside 2. Larger animals have low surface area to volume ratio- dif...

AQA A-Level Biology. 3.2 – Cells All Answers Correct Structure of Nucleus. 1. Nuclear envelope: double membrane surrounding nucleus, outer membrane continuous with the (R)ER of the cell. 2. Nuclear pores: allow the passage of larger molecules, such as mRNA, out of the nucleus. 3. Nucleoplasm: granular, jelly-like material making up the bulk of the nucleus. 4. Chromosomes: protein-bound, linear DNA. 5. Nucleolus: small spherical region(s) in nucleoplasm. Manufactures ribosomal RN...

AQA A level BIOLOGY 7402/3 Paper 3 Mark scheme June 2023. (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 4. Accep...

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 ion...

AQA A-level Biology Paper 1 Test || All Questions & Answers (100% Correct) AQA A-level Biology Paper 1 Test || All Questions & Answers (100% Correct) large molecules often contain carbon. why? - ANSWER - they can readily form bonds with other carbon atoms. this forms a 'backbone'. other atoms can then attach. describe benedicts test for reducing sugars - ANSWER - add equal volumes of the sugar sample and benedicts reagent. heat the mixture in a water bath for 5 minutes. brick red prec...

Biology AQA A level common questions latest 2023 with complete solutions give two factors other than age and gender that would affect the concentration of creatinine in the blood ? muscle/ body mass ethnicity Explain how the cells of the collecting duct are able to absorb water from the filtrate through the protein channels in their plasma membranes? lower w.p/ more negative inside tubule cells so h2o enters by osmosis Suggest why diabetes insipidus is more common in males ? Bc males onl...

AQA A-level BIOLOGY 7402/3 Paper 3 Mark scheme June 2023. (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 4. Accep...

AQA A-Level Biology Topic 3 Already Passed Why are Microorganisms able to perform exchange via their surface? • have a large surface area to volume ratio • have a short diffusion distance • have low demand How do Microorganisms Obtain Nutrients & Remove Waste? • by exchange via their surface • nutrients (e.g. glucose, oxygen) move in by diffusion via their surface • waste (e.g. carbon dioxide) move out by diffusion via their surface Why can't Animals/Plants perform exchange...

AQA A-Level Biology - Topic 3 (2022/2023) with Verified Answers Smaller organisms have a ........... surface area to volume ratio Higher How do single called organisms exchange substances? Diffuse directly into or out of the cell across the cell surface membrane Give 2 reasons why in multicellular organisms, diffusion across outer membrane would be too slow? 1. Some cells deep within body- big distance between them and outside 2. Larger animals have low surface area to volume ratio- diffi...

AQA A LEVEL BIOLOGY 4/5/6 MARK EXAM | QUESTIONS & 100% CORRECT ANSWERS (VERIFIED) | LATEST UPDATE | GRADEA+ Many different substances enter and leave a cell by crossing its cell surface membrane. Describe how substances can cross a cell surface membrane. (5) Correct Answer: 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 ...