Study guides, Class notes & Summaries

A vaccine can be used to produce immunity. Describe how memory cells are important in this process. (3) - CORRECT ANSWERS important because when individual is in contact with virus again, antibodies can be produced at a faster rate in a secondary immune response, and so the pathogen can be destroyed faster. abiotic - CORRECT ANSWERS non-living artery structure - CORRECT ANSWERS thick muscle layer so that they can dilate and contract to smooth blood flow. thick elastic layer so artery ...

AQA A-Level Biology Questions with Answers | Graded A Glucose is absorbed from the lumen of the small intestine into epithelial cells. Explain how the transport of sodium ions is involved in the absorption of glucose by epithelial cells. (5 marks) [Unit 1, June 16] - Correct Answer ️️ -1. Na+ ions leave epithelial cell and enter blood; 2. (Transport out is by) active transport / pump / via carrier protein using ATP; 3. So, Na+ conc. in cell is lower than in lumen (of gut); 4. Sodium/N...

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 – Enzymes Test Questions and Answers 100% Solved Activation Energy The minimum energy required for successful collisions to result in a reaction Enzyme Function Lowers the activation energy for a reaction to start, behaves as a catalyst Enzyme Structure Globular proteins that have a functional region known as an active site Active Site Functional region on an enzyme that is complimentary to substrates Complimentary Of a similar shape to one another

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 4/5/6 mark questions (2024/2025) Exam Questions and Answers 100% Solved 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; Small / non-polar / lipid-soluble molecules pass via phospholipids / bilayer; OR Large / polar / water-soluble molecules go through proteins; Water ...

AQA A level Biology - Topic 6 - survival and response questions and answers 100% Solved What is a stimulus? A change in the environment of an organism What is a tactic response? Directional movement in response to a stimulus What is a kinetic response? Non directional random movement in response to a stimulus What is a positive and negative taxis? Positive taxis- organism moves towards stimulus Negative taxis - organism moves away from stimulus What Are receptors? Detect stimuli- can ...

AQA A-level Biology paper 1 Questions and Answers 100% Solved large molecules often contain carbon. why? they can readily form bonds with other carbon atoms. this forms a 'backbone'. other atoms can then attach. describe benedicts test for reducing sugars add equal volumes of the sugar sample and benedicts reagent. heat the mixture in a water bath for 5 minutes. brick red precipitate will form. what is a reducing sugar? a sugar that can reduce (give electrons to) another chemical. des...

AQA A-Level Biology – Proteins Latest 2024/2025 Questions and Answers 100 Solved Amino Acid A monomer that will join with other amino acids to form a protein Dipeptide Two amino acids bonded together via a peptide bond Polypeptide Many amino acids bonded together via peptide bonds Protein A combination of polypeptides Amine Group -NH2, a basic group where the amino part of amino acid comes from Carboxyl Group -COOH, an acidic group where the acid part of amino acid comes from