science mock revision

• Homeostasis is the maintenance of a stable internal environment in the body, achieved through processes like negative feedback
• The nervous system moves instructions around the body through electrical impulses and during a reflex, a rapid, automatic response to a stimulus occurs without conscious thought
• Reaction time can be investigated by measuring the time it takes for a stimulus to produce a response
• The endocrine system uses hormones to transmit messages, while the nervous system uses electrical impulses; the endocrine system's messages are slower but longer-lasting compared to the nervous system
• The body regulates blood glucose levels through the hormones insulin and glucagon; diabetes is a condition where blood glucose levels are not properly regulated
• In the menstrual cycle, the uterus lining thickens in preparation for a fertilized egg; if fertilization does not occur, the lining is shed during menstruation
• To prevent pregnancy and the spread of STDs, methods like condoms, birth control pills, and regular STD testing can be used
• Possible treatments for infertility include medications to stimulate ovulation, intrauterine insemination, in vitro fertilization (IVF), or surgery
• Meiosis is a type of cell division that produces gametes with half the number of chromosomes as the parent cell
• Punnett squares are used to predict the possible genotypes and phenotypes of offspring based on the genotypes of the parents
• Some inherited disorders include cystic fibrosis, sickle cell anemia, and Huntington's disease
• Ecosystem keywords include habitat, niche, population, community, and ecosystem
• Biotic factors are living components of an ecosystem, while abiotic factors are non-living components
• Animal and plant adaptations are characteristics that help organisms survive and reproduce in their environment
• Food chains show the flow of energy from one organism to another in an ecosystem
• Quadrats and transect lines are used to sample and estimate populations of organisms in an ecosystem
• The carbon cycle involves the movement of carbon through the atmosphere, biosphere, geosphere, and hydrosphere; the water cycle describes the movement of water through the atmosphere, land, and oceans
• Biodiversity refers to the variety of life forms in an ecosystem and is important for ecosystem stability and resilience
• Global warming is the gradual increase in the Earth's temperature due to human activities releasing greenhouse gases into the atmosphere
• Deforestation is the clearing of forests on a large scale, often for agriculture, which can lead to habitat loss and environmental problems
• To measure and calculate rates of reaction, factors like the change in concentration over time can be used; graphs of rates of reaction show how the concentration of reactants or products changes over time
• Factors that affect rates of reaction include temperature, concentration, pressure, surface area, and the presence of catalysts
• Reversible reactions are chemical reactions that can proceed in both the forward and reverse directions
• Le Chatelier's Principle states that if a system at equilibrium is disturbed, the system will shift to counteract the disturbance
• Fractional distillation is a method used to separate a mixture of liquids with different boiling points
• Cracking is a process used in the petroleum industry to break down large hydrocarbon molecules into smaller, more useful ones
• Chromatography is a technique used to separate and analyze mixtures of substances in a lab; gas tests are experiments to identify the presence of specific gases
• Purity refers to the degree of impurities in a substance, while formulation describes the specific composition of a mixture or compound
• The evolution of the atmosphere involved the gradual accumulation of oxygen due to photosynthetic organisms; the greenhouse effect is the trapping of heat in the Earth's atmosphere by greenhouse gases, leading to climate change
• Common air pollutants include carbon monoxide, sulfur dioxide, nitrogen oxides, and particulate matter; the carbon footprint is the total amount of greenhouse gases emitted directly or indirectly by human activities
• Finite resources are limited in quantity and will eventually run out, while renewable resources can be replenished naturally; recycling is the process of converting waste materials into reusable objects
• Life cycle assessments analyze the environmental impact of a product throughout its entire life cycle, from raw material extraction to disposal; potable water is safe for drinking, and desalination is the process of removing salt from seawater to make it drinkable
• Wastewater can be treated through processes like filtration, biological treatment, and disinfection to remove contaminants before it is released back into the environment
• Contact forces require physical contact between objects, like friction or tension, while non-contact forces, such as gravity or magnetic forces, act at a distance
• Scalars are quantities that have only magnitude, while vectors have both magnitude and direction; resultant forces or vectors are the sum of all forces acting on an object
• Hooke's law states that the extension of a spring is directly proportional to the force applied to it, as long as the elastic limit is not exceeded
• Velocity is the rate of change of displacement, displacement is the change in position of an object, and acceleration is the rate of change of velocity
• Distance-time graphs show how distance changes over time, while velocity-time graphs show how velocity changes over time; Newton's Laws describe the relationship between the motion of an object and the forces acting on it
• Stopping distances depend on the thinking distance (reaction time) and braking distance; reaction times can be affected by factors like tiredness or distractions
• Transverse waves have vibrations perpendicular to the direction of wave travel, while longitudinal waves have vibrations parallel to the direction of wave travel