Biology Revision - Year 9 PDF

The connection between photosynthesis and cellular respiration: Photosynthesis makes glucose which is used in cellular respiration for making ATP (energy). The word formula and chemical formula for cellular respiration and photosynthesis: Cellular respiration: Word equation - oxygen + glucose --->...

The connection between photosynthesis and cellular respiration: Photosynthesis makes glucose which is used in cellular respiration for making ATP (energy). The word formula and chemical formula for cellular respiration and photosynthesis: Cellular respiration: Word equation - oxygen + glucose ---> water + carbon dioxide + ATP(energy) Chemical formula - c6H12O6+6O2 →6CO2+6H2O+ATP Photosynthesis: Word equation - water + carbon dioxide (+light) ---> oxygen + glucose Chemical formula - 6CO2+6H2O →C6H12O6+6O2 The reactants and products of cellular respiration and photosynthesis Examples of abiotic and biotic factors: Abiotic factors: Amount of light available, Temperature, Precipitation, Oxygen availability, Humidity of the air Biotic factors: Competition, Dispersal, Predation, Human intervention Understand the difference between a species, population, community, environment and habitat: Species is defined as a group of organisms that consist of similar individuals capable of interbreeding or exchanging genes among themselves. A population is a group of organisms of the same species living in the same geographic area at the same time. A community is all the living things , plants and animals, living together in that specific area or ecosystem. The environment is the surroundings of an organism including the physical and chemical environment, and other organisms with which it comes into contact. A habitat is the natural home or environment of a plant, animal, or other organism. Understand the difference between a producer, consumer and decomposer: Producers, or autotrophs, are organisms that can make their food, such as trees, shrubs, grass, algae etc. All of these are green in colour because they contain chlorophyll that absorbs the energy from the sun and uses it to produce its food. This is known as photosynthesis. Consumers, or heterotrophs, are organisms that consume other organisms to obtain their energy. A decomposer is an organism, often a bacterium or fungus that feeds on and breaks down dead plant or animal matter, making organic nutrients available to the ecosystem. Identify the 3 relationships between different species and give examples: Predator-prey (fox and rabbit), Symbiosis, Interspecific competition (Woodpeckers and squirrels frequently compete for nesting sights in the same holes in trees) Symbiosis: Commensalism (Whales And Barnacles) – where one species benefits while the other is unaffected. Mutualism (Oxpecker and Zebra) – both species benefit. Parasitism (Ticks and Dogs) – one species benefits while one is harmed. Identify the 3 relationships within species and give examples: Mating (Mule = Horse + Dog), Collaboration (bees in a hive), Intraspecific competition (two male donkeys fighting for mates) identify the 5 key human impacts on ecosystems (CHIPP) C- Climate Change H- Habitat Loss I- Introduced Species P- Population P- Poaching BIOLOGY The cell theory and the organisation of living things (cells, tissues, organs, organ systems, organisms): Function of endocrine system: The system responsible for releasing hormones into the body via the bloodstream. A hormone is a chemical messenger that can change the activity of a cell. They are produced by organs called endocrine glands. The circulatory system carries hormones throughout the body and so they come in contact with all body cells, but only certain target cells respond to a given hormone. Glands and associated hormones: Hormones are the chemical signalling molecules produced by the endocrine glands and secreted directly into the bloodstream. Homeostasis and negative vs positive feedback: Homeostasis is a system's ability to maintain a stable state when its surroundings change. The optimal level for homeostasis is known as the set point. Negative feedback systems restore/return the body to the set point by reducing the effect of the original stimulus, so they are ideal for maintaining homeostasis. Positive feedback systems increase the condition by increasing the effect of the original stimulus. Stimuli: A stimulus is a detectable change in the physical or chemical structure of an organism's internal or external environment. Stimulus response models, including negative feedback: Function of the nervous system, including the CNS (Central Nervous System) and PNS (Peripheral Nervous System) and the structures/bones that protect them: Central nervous system The central nervous system consists of the brain and spinal cord and it includes receiving, processing, and responding to sensory information. The brain is protected by the cranium, and the spinal cord by vertebrae. Peripheral nervous system The peripheral nervous system is made up of nerves that branch off from the spinal cord and extend to all parts of the body. Your PNS feeds information into your brain from most of your senses. It carries signals that allow you to move your muscles. The PNS has no protection. Parts of a neuron (and how to label them): Types of sensory receptors (chemoreceptors, photoreceptors, mechanoreceptors, thermoreceptors etc) We receive information all the time about our environment from receptors. Some receptors are concentrated into a small area and organised into a structure called a sense organ, such as the eye, while others are distributed throughout the body surface, such as heat, pain and touch receptors. Mechanoreceptors: hearing, balance, pressure, touch etc. Chemoreceptors: taste, smell, communication Photoreceptors: light, vision Thermoreceptors: temperature Types of neutrons (sensory, inter, motor) and what they do: Affector (sensory) neurons have one or more receptors that detect change in the environment. Information detected is transmitted (sent) as an electrical impulse to the CNS by the affector neuron. Effector (motor) neurons carry impulses away from the CNS to muscle cells or glands and cause them to respond. Connecting neurons (interneurons) are typically located in the CNS and link sensory and effector neurons How reflex arcs work: The simplest and quickest nerve pathway where a message bypasses the brain to keep the body safe. In a reflex arc, the sensory neuron sends a signal to the interneuron and activates it. The interneuron then relays that signal to the next neuron, a motor neuron. Motor neurons connect with interneurons in the spinal cord. They send messages from the central nervous system to the body. Pathogens vs microbes: A pathogen is something that causes a disease or infection (eg. a virus, fungus or bacterium). Microbes are microscopic organisms, i.e. they are living. 3 lines of defence, including examples of each: 1st Line of Defence: Barriers - skin, bodily fluids like mucus, tears, stomach acid, actions such as sneezing/coughing/vomiting 2nd Line of Defence: General Immune Response - fever/temporary change in the body’s set point, white blood cells cause inflammation and phagocytes engulf and destroy foreign bodies. 3rd Line of Defence: Specific Immune Response - specialised white blood cells called B Cells produce antibodies. Antibodies are the molecules produced by an organism’s immune system to fight a specific antigen. An antigen is a marker on a pathogen that has a specific shape, causing specific antibodies to be produced. Types of disease (infectious vs non-infectious, contagious vs non-contagious): Diseases caused by pathogens are called infectious diseases (they can be caught, eg. chicken pox, the flu, a cold, COVID-19). Diseases that are hereditary (inherited), caused by the environment, or caused by lifestyle factors are non-infectious (they are not caused by pathogens, you cannot catch them eg. lung cancer from smoking, hives from an allergic reaction to perfume). Contagious diseases can be spread from person to person (eg. the flu, chickenpox). Non-contagious diseases are still infectious, but cannot be spread from person to person (eg. malaria is spread by mosquito). Antigens and antibodies: An antigen is a foreign substance that enters your body. This can include bacteria, viruses, fungi, allergens, venom and other various toxins. An antibody is a protein produced by your immune system to attack and fight off these antigens.