AQA GCSE Biology - Paper 1 Exam Questions With 100% Correct Answers

AQA GCSE Biology - Paper 1 Exam Questions With 100% Correct Answers What does a nucleus do? - answerIt contains genetic material and controls the activities of the cell What does cytoplasm do? - answerIt'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? - answerIt holds the cell together and controls what goes in and out What do mitochondria do? - answerThese are where most of the reactions for aerobic respiration occur. Respiration transfers energy that the cell needs to work What do ribosomes do? - answerThis is where protein synthesis takes place - where proteins are made in the cell What do cell walls do? - answerThey are made of cellulose and they support and strengthen the cell What does a vacuole do? - answerIt contains cell sap and helps maintain the shape of the cell What do chloroplasts do? - answerThis 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? - answerCytoplasm, 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? - answerA nucleus What is the equation for magnification? - answerImage size divided by actual size What is differentiation? - answerThe process by which a cell changes to become specialised for its job What are undifferentiated cells called? - answerStem cells What are sperm cells specialised for and how are they specialised? - answerReproduction - 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? - answerRapid 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? - answerContraction - 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? - answerAbsorbing 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? - answerCoiled up lengths of DNA molecules that are found in the nuclei What is mitosis? - answerThe stage of the cell cycle where the cell divides What do multicellular organisms use mitosis for? - answerTo grow or replace cells that have been damaged Describe each stage of mitosis - answerProphase - The chromosomes shorten and duplicate Metaphase - The chromosomes line up on the equator of the cell Anaphase - The chromosomes are pulled to the opposite ends of the cell. The chromatids are now known as daughter cells. Telophase - New membranes form around the daughter nuclei which becomes the nuclei of the two new cells - the nucleus has divided. The cytoplasm and cell membrane divide to create two daughter cells. What are stem cells? - answerThey are undifferentiated cells that divide to produce lots more undifferentiated cells. They then differentiate into different types of cell Where are stem cells found? - answerIn early human embryos or the bone marrow of adults What do embryonic stem cells do? - answer1) 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 Where are stem cells found in plants? - answerMeristems What is diffusion? - answerDiffusion 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 - answerGlucose, water, oxygen and amino acids Name two substances that can't diffuse through cell membranes - answerProtein and starch What is osmosis? - answerOsmosis is the passive movement of water molecules through a partially permeable cell membrane from an area of high water concentration to an area of low water concentration What are the two main differences between active transport and diffusion? - answerActive transport uses energy whereas diffusion doesn't. Active transport goes against the concentration gradient whereas diffusion goes along it Adaptations of Exchange Surfaces - answer1) Large surface area - lots of substances can diffuse at once 2) Lots of blood vessels - to get stuff into and out of the blood quickly 3) Thin membrane - short distance for substances to diffuse 4) Often ventilated - air moves in & out Give two ways that the villi in the small intestine are adapted for absorbing digested food - answer1) A single layer of surface cells 2) A very good blood supply to assist quick absorption Explain how the leaves are adapted to maximise the amount of carbon dioxide that gets into their cells - answer1) The exchange surface in a leaf is covered in stomata which the carbon dioxide diffuses through 2) The leaf has a flattened shape which increases the area of its exchange surface, therefore it's more effective 3) The walls of the cells inside the leaf act as another exchange surface 4) The air spaces inside the leaf increase the area of the exchange surface which increases the chance for carbon dioxide to enter the cells