Biology GCSE

• What is photosynthesis?

  Photosynthesis is the process that plants use to make glucose.
• How could you investigate the effect of exercise on breathing and heart rate?

  -You can measure breathing rate by counting breaths and heart rate by taking a pulse. -You could exercise for 5 minutes doing three different exercises of different intensities. After each exercise take your pulse and heart rate. -Your pulse rate will increase the more intense the exercise is as your body needs to get more oxygen to the muscles ad take away the carbon dioxide.
• How do you calculate cardiac output?


  Cardiac output = heart rate * stroke volume
• Why is it important that you breathing rate increases during exercise?

  Your breathing rate increases to get more oxygen into the blood around the body so your heart rate increases. This removes CO2 more quickly at the same time.
• Why do you respire more during exercise?

  Muscles need energy from respiration to contract. When you exercise some of your muscles contract more frequently than normal so you need more energy. This energy comes from increased respiration. The increase in respiration means you get more oxygen to the cells.
• Why is diffusion needed?

  -When cells respire they use up oxygen and glucose, so the concentration of these inside the cells is low. The concentration of these substances in the blood is higher, so they diffuse from the capillaries into the cells. -When cells respire they produce carbon dioxide therefore the concentration is high. The carbon dioxide diffuses from the cells into the blood where the concentration is lower.
• When is diffusion used?


  Many substances enter and leave the body by diffusion. These substances include gases such as oxygen and carbon dioxide, and small digested food molecules such as glucose.
• What is diffusion?

  Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.
• What is EPOC?

  EPOC (excess post-exercise oxygen consumption) is the amount of oxygen needed after exercise has ended compared with the resting rate.
• What is the disadvantage to using anaerobic respiration?

  -Anaerobic respiration releases much less energy from each molecule of glucose than aerobic respiration. -Lactic acid is not removed from the body. It builds up in muscle and blood, and must be broken down after exercise.
• What is the advantage to using anaerobic respiration?

  You can keep on using your muscles for longer. Anaerobic respiration is useful for muscle cells because it can release energy to allow muscles to contract when the heart and lungs cannot deliver oxygen and glucose fast enough for aerobic respiration.
• When is anaerobic respiration used?

  Anaerobic respiration happens when there's not enough oxygen available. Anaerobic respiration does not release as much energy as aerobic respiration. It also produces build up of lactic acid in the muscles which gets painful and can give you cramp.
• What is the word equation for anaerobic respiration?

  Glucose = lactic acid (+energy)
• What is anaerobic respiration?

  Anaerobic respiration is the release of energy from glucose without using oxygen. This produces lactic acid.
• What is the word equation for aerobic respiration?

  Glucose + Oxygen = Carbon dioxide + water (+energy)
• What is aerobic respiration?

  Aerobic respiration uses oxygen from the air to release energy from glucose.
• What is the energy from respiration used for?

  - Growth and movement - Build up larger molecules (like proteins)- Contract muscles - Maintain a steady body temperature
• What is respiration?

  Respiration is the process used by all living organisms to release energy from organic molecules. Respiration is how all living things get energy from food.
• What is a risk of using stem cells?

  They may produce cancer cells instead of healthy cells
• What are the disadvantages of adult stem cells?

  -They are difficult to find and extract from tissue-They produce only a few types of cell
• What are disadvantages to using embryonic stem cells?

  -The embryo is destroyed when the cells are removed and some people think embryos have a right to life- The body recognises the cells are different and will reject them without the use of drugs.
• What are adult stem cells?

  Adult stem cells are found in differentiated tissue, such as bone or skin - they divide to replace damaged cells. No embryo is destroyed so there's no ethical issue. If adult stem cells are taken from the person to be treated, it will not cause rejection to the body.
• What are embryonic stem cells?

  Embryonic stem cells are taken from embryos that contain only a few cells. The cells in the embryo are all the same (undifferentiated). Stem cells are easy to extract from an embryo. They can also produce any type of cell.
• What are stem cells?

  Stem cells are cells that can divide to produce many types of cell. There are two kinds of stem cell; embryonic and adult stem cells.
• What are the disadvantages of cloning and some issues surrounding cloning?

  - Any genetic defect in the parent will be passed on to the offspring- Clones mammals may suffer more health problems than usual, which may cause them to die early - It is more difficult to clone a mammal than a plant; it may take a few attempts- Cloning mammals leads to a reduced gene pool (fewer alleles in the population). This may mean if there is a new disease all the species could become extinct
• What are the advantages of cloning?

  - If the animal that is cloned has good features, all of its offspring will have the same good features. - Cloning mammals can help with the shortage of organs for transplants- Cloning can be used to help preserve endangered species
• How is cloning done?

  1) The nucleus is removed from an egg cell 2) The diploid nucleus is removed from an adult body cell.3) The diploid nucleus from the body cell is placed inside the empty egg cell. The cell is then stimulated with an electric pulse to start mitotic division. 4) The cell divides and grows as an embryo 5) The embryo is placed in the uterus of a surrogate mother until it is ready to be born.
• What are clones?

  Clones are organisms that have identical genes.
• What is cloning?

  Cloning is a type of asexual reproduction. It produces cells that are genetically identical to an original cell.
• What happens during sexual reproduction?

  During sexual reproduction, two gametes for a new cell which will grow to become a new organism. The two gametes combine (sperm and egg) to produce a zygote (fertilised egg). Sexual reproduction produces variation in the offspring.
• What happens during meiosis?

  As with meiosis, before the parent cell begins to divide, each chromosome is copied. The cell divides in two and then in two again. Four daughter cells are produces. Each daughter cell gets a copy of one chromosome from each pair. Each daughter cell has only one set of chromosomes therefore these are haploid cells. The daughter cells are not all identical - meiosis results in variation.
• What is meiosis?

  Meiosis is when a cell divides to produce four haploid nuclei whose chromosomes are NOT identical. Meiosis only happens in reproductive organs e.g ovaries
• Why are gametes haploid?

  So that when two gametes combine at fertillisation, the resulting cell (zygote) has the right number of chromosomes. Zygotes are diploid - they have two copies of each chromosome.
• What are haploid cells?

  Haploid cells have only one copy of each chromosome. Gametes are haploid.
• What are gametes?

  Gametes are 'sex cells'. They are called ova (single ovum) and sperm in males. During sexual reproduction, two gametes combine to form a new cell which will grow to become a new organism.
• When might asexual reproduction happen?


  -When bacteria split to make more bacteria-When plants make new plantlets that split off from the parent plant to grow on their own.
• What is asexual reproduction?

  Asexual reproduction is the production of new organisms without fertilisation. The offspring have exactly the same genes as the parent - so there's no genetic variation.
• What are situations where mitosis is used to produce new cells?

  -Growth-Repairing damaged parts of the body -Asexual reproduction
• What are the stages of mitosis?


  -The parent cell is a diploid cell (it has two sets of chromosomes). Before the parent cell divides, each chromosome is copied exactly. The parent cell divides to form two daughter cells that are genetically identical to each other and the parent cells (these are also diploid cells)
• What is mitosis?


  How cells divide for growth and repair. This happens when humans, animals and plants want to grow or replace cells that have been damaged.