China 高二 Biology
Chapters: 9
1. Sel.1 Ch.1 Internal environment
Body fluids and internal environment · Homeostasis (glucose, temperature, pH, osmolarity)
- Body Fluids and Circulation – Blood and lymph are the body's transport fluids. Blood is plasma (about 55%) plus formed elements: RBCs, WBCs and platelets. Blood groups (ABO, Rh) depend on antigens on RBCs. A clot forms when fibrinogen turns into fibrin threads. The human heart has four chambers and pumps blood through two loops: to the lungs and to the body (double circulation). The SA node starts each beat; one beat is a cardiac cycle of about 0.8 s, recorded as an ECG with P, QRS and T waves. Cardiac output = stroke volume × heart rate ≈ 5 L/min.
- Homeostasis – Homeostasis is how the body keeps its internal environment (blood and tissue fluid) steady even when the outside world changes. It controls body temperature (about 37 °C), blood glucose (about 4–6 mmol/L), water and salt, and blood pH (about 7.4). It mostly uses negative feedback: a receptor senses a change, a control centre decides, and an effector brings the level back to its set point.
2. Sel.1 Ch.2 Nervous regulation
Structure of the nervous system; reflex · Nerve impulse; synapses · Hierarchical control; higher brain functions
- Neural Control and Coordination – Coordination means organs working together. The nervous system does this fast, using neurons. A neuron has a cell body, dendrites and an axon; many axons have a myelin sheath with nodes of Ranvier. The central nervous system (brain and spinal cord) processes information; the peripheral nervous system (nerves) carries it. The PNS has a somatic part (skeletal muscles) and an autonomic part (sympathetic and parasympathetic) for internal organs, the visceral system. At rest the axon is polarised: inside −, outside +, about −70 mV. A stimulus lets Na+ rush in, creating an action potential that travels along the axon. At a synapse, neurotransmitters carry the signal to the next neuron.
3. Sel.1 Ch.3 Humoral regulation
Hormones and endocrine system · Feedback and hierarchical regulation · Nervous–humoral cooperation (temperature, water balance)
- Chemical Coordination and Integration – Hormones are chemical messengers made in tiny amounts by ductless (endocrine) glands. They travel in blood and act on target cells that have the right receptor. The hypothalamus controls the pituitary, which controls many other glands; negative feedback keeps levels steady. Main glands: pineal, pituitary, thyroid, parathyroid, thymus, adrenal, pancreas (islets), testis and ovary. The heart, kidney and gut also make hormones. Protein hormones act through membrane receptors and second messengers like cAMP; steroid and thyroid hormones enter the cell and change gene expression. Too little (hypo-secretion) or too much (hyper-secretion) of a hormone causes disorders like dwarfism, gigantism, goitre, diabetes, Addison's disease and Cushing's syndrome.
4. Sel.1 Ch.4 Immune regulation
Immune system · Specific immunity (humoral, cellular) · Immune disorders (allergy, autoimmunity, HIV) · Applications (vaccines, transplants)
- Human Health and Disease – Health means the body, mind and social life all work well. Diseases can be caused by germs (pathogens) like bacteria, viruses, protozoa, worms and fungi. Our body fights them with two kinds of immunity: innate (we are born with it) and acquired (it learns and remembers). Vaccines use this memory. HIV destroys helper T cells and causes AIDS. Cancer is cells dividing without control. Drugs and alcohol harm the body and mind, especially in teenagers.
5. Sel.1 Ch.5 Plant regulation
Auxin · Other plant hormones · Plant growth regulators · Environmental factors (light, gravity, temperature)
- Plant Growth and Development – Growth is a lasting increase in size. A seed germinates when it gets water, oxygen and the right temperature. At root and shoot tips cells divide, then get longer, then mature. Growth can be arithmetic (same amount each day) or geometric (a share of what is there), which gives an S-shaped curve. Cells then specialise (differentiate), can go back to dividing (dedifferentiate) and specialise again (redifferentiate). Five hormone groups, auxin, gibberellin, cytokinin, ethylene and ABA, control it all.
6. Sel.2 Ch.1 Populations
Population characteristics; density surveys · Population growth models (J, S) · Factors affecting populations
- Organisms and Populations: Growth and Interactions – A population is a group of the same species living in one area at one time. It has features that a single organism does not have: density, birth rate, death rate, sex ratio and age structure. N grows by births and immigration and shrinks by deaths and emigration. With unlimited food it grows fast (J-curve, dN/dt = rN); with limited food it slows and stops at the carrying capacity K (S-curve, dN/dt = rN(1 − N/K)). Different species affect each other: mutualism (+/+), competition (−/−), predation and parasitism (+/−), commensalism (+/0) and amensalism (−/0).
7. Sel.2 Ch.2 Communities
Community structure · Main community types · Succession
- Organisms and Populations: Growth and Interactions – A population is a group of the same species living in one area at one time. It has features that a single organism does not have: density, birth rate, death rate, sex ratio and age structure. N grows by births and immigration and shrinks by deaths and emigration. With unlimited food it grows fast (J-curve, dN/dt = rN); with limited food it slows and stops at the carrying capacity K (S-curve, dN/dt = rN(1 − N/K)). Different species affect each other: mutualism (+/+), competition (−/−), predation and parasitism (+/−), commensalism (+/0) and amensalism (−/0).
- Community Types: Desert, Grassland and Forest – A community is all the living things (plants, animals, fungi, microbes) of different species that live together in one place. Its type depends mostly on climate, above all on water. Dry places form desert communities, medium-wet places form grassland communities and wet places form forest communities. Each has its own plants, animals and layers.
- Ecosystems in Depth: Biomes, Nutrient Cycles and Disruption – Biomes are large regions with similar climate and life. On land, temperature and rainfall decide the biome; in water, salt, depth, light and flow decide the zones. Matter cycles through ecosystems: nitrogen moves between air, soil, organisms and back through fixation, nitrification, assimilation, ammonification and denitrification; phosphorus cycles slowly between rock, soil, water, organisms and sediment with no gas stage. Decomposers recycle matter with oxygen (aerobic) or without it (anaerobic). Human actions such as fertiliser runoff, habitat loss, invasive species and climate change disrupt these systems; ecosystems respond with resistance and resilience.
8. Sel.2 Ch.3 Ecosystems
Structure · Energy flow · Matter cycling; biomagnification · Information transfer · Stability
- Ecosystem: Structure, Productivity, Energy Flow and Pyramids – An ecosystem is a working unit of nature where living things (biotic) and non-living things (abiotic) interact. Plants make food at a rate called productivity: gross (GPP) minus respiration gives net (NPP = GPP − R). Dead matter is broken down in five steps: fragmentation, leaching, catabolism, humification and mineralisation. Energy enters as sunlight, flows one way through trophic levels and only about 10% passes on each time. Ecological pyramids of number, biomass and energy show this; number and biomass pyramids can be inverted, but the energy pyramid is always upright.
- Ecosystem, Food Chains and Energy Flow – An ecosystem is all the living things in a place plus the non-living things around them, working together. Energy enters as sunlight, passes one way up a food chain, and only about 10% moves to each next level.
- Information Transfer in Ecosystems – Living things in an ecosystem keep sending messages to each other. There are three kinds. Physical information uses sound, light and colour. Chemical information uses smell and other substances such as pheromones. Behavioural information uses actions such as dances and displays. These messages help animals find food, find mates, warn of danger and keep populations in balance. Unlike energy, information can flow in both directions.
- Atmospheric Stability and Adiabatic Processes – When a parcel of air rises, the pressure around it falls, so it expands and cools without gaining or losing heat: adiabatic cooling. Dry (unsaturated) air cools 10 °C per km (dry adiabatic lapse rate). After it reaches its dew point, vapour condenses into cloud and releases latent heat, so it cools only about 4 to 7 °C per km (saturated or moist adiabatic lapse rate, about 6). The surrounding air has its own environmental lapse rate (average 6.5 °C per km). If a rising parcel becomes colder than its surroundings, it is heavier and stops: stable air, flat clouds, fog and smog. If it stays warmer, it keeps rising: unstable air, tall cumulus and thunderstorms. Between the two rates the air is conditionally unstable. An inversion (air warmer higher up) is very stable.
9. Sel.2 Ch.4 Humans and environment
Human impact; ecological footprint · Biodiversity and its protection · Ecological engineering
- Environmental Issues: Causes, Effects and Solutions – Environmental issues are harmful changes to air, water, land, climate and living things, mostly caused by human activity. The big ones are air pollution, water pollution, land pollution and waste, climate change, deforestation and loss of biodiversity, and overuse of resources. They grow with the number of people and how much each person uses (the ecological footprint). We can reduce them with clean energy, saving and recycling, treating waste water, protecting forests and good laws, at home, in the city, in the country and across the world.
- Biodiversity and its Conservation – Biodiversity is the variety of life at three levels: genetic, species and ecological. It is highest near the equator and grows with area (log S = log C + Z log A). Every species matters, like rivets on a plane. We are losing species fast because of the 'evil quartet': habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinction. The IUCN Red List (Red Data Book) ranks species from Least Concern to Extinct. We protect life in situ (hotspots, national parks, sanctuaries, biosphere reserves, sacred groves, Ramsar wetlands) and ex situ (zoos, botanical gardens, seed and gene banks).
- Ecological Engineering – Ecological engineering means designing human activities so that they work together with natural ecosystems instead of against them. Its main principles are: use the self-cleaning and self-regulating power of nature, recycle waste so that nothing is thrown away, keep many kinds of living things together, and balance people's needs with the health of the ecosystem. Examples are the mulberry-dike fish pond, constructed wetlands that clean waste water, wastewater fish ponds, and replanting mangroves.