AQA GCSE Biology - Paper 1 EXAM (2024)

What does a nucleus do? - It contains genetic material and controls the activities of the cell What does cytoplasm do? - It's a gel-like substance where most of the chemical reactions happen. It contains enzymes that control these chemical reactions What does a cell membrane do? - It holds the cell together and controls what goes in and out What do mitochondria do? - These are where most of the reactions for aerobic respiration occur. Respiration transfers energy that the cell needs to work What do ribosomes do? - This is where protein synthesis takes place - where proteins are made in the cell What do cell walls do? - They are made of cellulose and they support and strengthen the cell What does a vacuole do? - It contains cell sap and helps maintain the shape of the cell What do chloroplasts do? - This is where photosynthesis occurs, which makes food for the plant. They contain chlorophyll - a green pigment - which absorbs light needed for photosynthesis What do bacterial cells contain? - Cytoplasm, cell membrane, cell wall, flagella, ribosomes, mitochondria, slime capsule, plasmids (small rings of DNA) and a single circular strand of DNA that floats freely in the cytoplasm What do bacterial cells NOT contain? - A nucleus What is the equation for magnification? - Image size divided by actual size What is differentiation? - The process by which a cell changes to become specialised for its job What are undifferentiated cells called? - Stem cells What are sperm cells specialised for and how are they specialised? - Reproduction - they transport the male DNA to the female DNA -It has a flagella and a streamlined head to help it swim towards the egg -There are lots of mitochondria in the cell to provide the energy needed -It carries enzymes in its head to help digest through the egg cell membranes What are nerve cells specialised for and how are they specialised? - Rapid signalling - they carry electrical signals from one part of the body to another -They are long to cover more distance -They have branched connections at their ends to connect to other nerve cells and form a network throughout the body What are muscle cells specialised for and how are they specialised? - Contraction - they need to contract quickly -They are long so they have space to contract -They contain lots of mitochondria to generate the energy needed for contraction What are root hair cells specialised for and how are they specialised? - Absorbing water and minerals -They are cells on the surface of plant roots which grow into long hairs that stick out into the soil -They have a large surface area for absorbing water and mineral ions from the soil What are chromosomes? - Coiled up lengths of DNA molecules that are found in the nuclei What do multicellular organisms use mitosis for? - To grow or replace cells that have been damaged What are stem cells? - They are undifferentiated cells that divide to produce lots more undifferentiated cells. They then differentiate into different types of cell Where are stem cells found? - In early human embryos or the bone marrow of adults What do embryonic stem cells do? - 1) Used to replace faulty cells in sick people - insulin- producing cells for diabetes and nerve cells for paralysed spinal injuries 2) Used to replace faulty blood cells What is diffusion? - Diffusion is the movement of particles from an area of high concentration to an area of low concentration Name the substances that can diffuse through cell membranes - Glucose, water, oxygen and amino acids Name two substances that can't diffuse through cell membranes - Protein and starch