biology paper 2

• What is mitosis? A type of cell division which produces 2 identical daughter cells
• Diagram of mitosis
• What is a chromosome? Chromosomes are thin strands of DNA located in the nucleus
• What is homeostasis? Homeostasis is the maintenance of a constant internal environment to maintain optimum conditions for function
• Why is homeostasis important? Homeostasis is important because certain conditions are required for the body to function correctly and if they aren't met, the body could fail
• Examples of homeostasis in the human body - Body temperature - Water levels - Blood glucose levels
• What are receptors? Cells that detect changes in the internal or external environment
• What is a stimuli? A stimuli is a change in the environment
• 3 components of the body's automatic control system - Receptors - Effectors - Coordination centres
• Examples of coordination centres Brain, spinal cord or pancreas
• What is an effector? Muscles or glands that bring about a response to the stimulus that has been received
• What is a coordination centre? Areas that receive and process from the receptors, sending out signals to coordinate a response
• What is a negative feedback loop? A negative feedback control system responds when conditions change from the ideal or set point and returns conditions to this set point. There is a continuous cycle of events in negative feedback.
• Diagram of a negative feedback loop
• Example of negative feedback loop in the body Body temperature is controlled by the hypothalamus in your brain, and if your body gets too hot, your body begins to sweat to try and reduce it. However if the body gets too cold, it begins to shiver to try and raise the temperature.
• Diagram of a nerve cell (neurone)
• Which type of neurone transmits a signal from a sense organ to the central nervous system? Sensory neurones
• What is a synapse? A synapse is the gap at the junction of two neurones.
• What is the nervous system? The nervous system is a system that allows all the parts of the body to communicate with each other, enabling humans to react to their surroundings and to coordinate their behaviour.
• What does the nervous system use to help body parts communicate? Electrical impulses
• What is the CNS (Central Nervous System) made up of? Brain and spinal cord
• What is a motor neurone? A neurone that carries electrical imuplses from the CNS to effectors
• Stimulus response diagram
• Stages of a reflex arc
• What are relay neruones? A relay neuron allows sensory and motor neurons to communicate with each other. They are found in the CNS.
• What is a reflex? A reflex is a rapid automatic response to a stimulus
• What is a hormone? A hormone is a chemical substance, produced by a gland and carried in the bloodstream, which alters the activity of specific target organs.
• Differences in nervous and hormonal control
• What is the endocrine system? The endocrine system is a system which consists of glands and organs that make hormones and release them directly into the blood so they can travel to tissues and organs.
• Key endocrine glands Thyroid, pancreas, testes, ovaries and pituitary
• What is the role of the thyroid? To control the metabolic rate of the body
• What is the role of the pancreas in the endocrine system? To control the glucose levels in the blood
• What is the role of the adrenal gland? Produces adrenaline needed for the preparation of a flight or fight response
• What is the role of the pituitary gland? Controls growth in children Stimulates the thyroid gland to make thyroxine Stimulates the testes to make sperm Stimulates the ovaries to produce and release eggs
• What is insulin? Insulin is a hormone - produced by the pancreas - that regulates glucose concentrations in the blood.
• Negative feedback loop of blood glucose levels using glucagon and insulin
• What is type 1 diabetes? Type 1 diabetes causes the level of glucose (sugar) in your blood to become too high. It happens when your body cannot produce enough of a hormone called insulin, which controls blood glucose. You need daily injections of insulin to keep your blood glucose levels under control.
• What is type 2 diabetes? Type 2 diabetes is a lifelong disease that keeps your body from using insulin the way it should. People with type 2 diabetes are said to have insulin resistance. This is not a genetic disorder.
• How can type 2 diabetes be caused? Type 2 diabetes can be caused by lack of exercise and a poor diet. It is not inherited.
• Which hormones are produced in the male and female reproductive organs? Testosterone and oestrogen