Spain 1º Bachillerato Biology, Geology and Environmental Sciences
Chapters: 7
1. Scientific project
Scientific questions and hypotheses · Searching and communicating science · Reliable information sources · Lab and field experiments · Analysing scientific results · Science communication · Scientists and their work · History of scientific knowledge
- The Scientific Method – The scientific method is the careful way scientists find out how the world works. Observe something, ask a testable question, make a hypothesis (a clear, testable guess), test it with a fair experiment (change one variable, measure one, keep the rest the same), repeat and record data, analyse it, draw a conclusion and share it so others can check. Results that fail the test are useful too: they send you back to a new hypothesis.
- Research Skills: From a Question to a Finished Project – Research is a careful way of finding an answer. You ask a clear, focused question, plan how to answer it, find information and check that each source can be trusted, collect and analyse your own data, draw a conclusion that the evidence supports, and share it while crediting every source you used.
- Data Analysis – Data analysis means turning raw data into answers. It follows a cycle: ask a question, collect data, clean it (remove errors, repeats and blanks), organise and transform it, analyse it with summaries such as mean, median, range and patterns, show it with a good chart, and draw a careful conclusion. Watch for outliers, small samples and bias, and remember that a correlation between two things does not prove that one causes the other. Data must also be stored safely and used with permission.
- Communication Skills: How to Share Meaning Clearly and Kindly – Communication is sharing meaning between people. A sender encodes an idea into a message, sends it through a channel, and a receiver decodes it and gives feedback. Barriers such as noise, hard words, strong emotions and cultural differences can block or bend the message. We send meaning with words (verbal), with face, eyes, gestures, posture and tone (non-verbal), and with pictures (visual). Active listening — attention, patience, questions and paraphrasing — proves the message arrived. Good communicators adapt to context: formal or informal, spoken or written, and use polite requests, kind refusals, sincere apologies and assertive (not aggressive or passive) language.
- Nature of Science: How Scientific Knowledge Is Built and Changed – Science is a way of knowing that rests on evidence anyone can check. Scientists observe, infer, test ideas that could be proved wrong, and let other experts check their work. Laws describe what happens; theories explain why. Scientific knowledge is reliable but always open to change, and sometimes a whole way of seeing (a paradigm) is replaced.
2. Ecology and sustainability
Environment, economy and One Health · Sustainability of daily activities · Initiatives for sustainable development · Ecosystem dynamics · Climate change and carbon cycle · Biodiversity loss · Waste and xenobiotics
- Environmental Health – Environmental health is about how our surroundings — air, water, food, soil, chemicals, noise, heat and the buildings we live in — affect our health. Harm reaches the body by four roads: breathing, drinking, eating and touching. Risk depends on the dose and how long we are exposed. Some poisons build up along food chains. The One Health idea says human, animal and environmental health are linked, so we protect all three together.
- Sustainability – Sustainability means meeting our needs today without taking away the ability of future people to meet theirs. It rests on three pillars — environment, society and economy. A resource is used sustainably when we use it no faster than it renews. Today humanity uses about 1.7 Earths' worth of resources a year, and this use is very unequal. Stewardship, careful planning and spatial tools like GIS help us move towards sustainability.
- Environment and Sustainable Development – The environment gives us resources, soaks up our waste, supports life and gives beauty. When we take resources faster than nature renews them, or throw waste faster than it can absorb, we cross its carrying capacity and face an environmental crisis. India faces land degradation, air and water pollution, forest and biodiversity loss. Burning fossil fuels traps heat and causes global warming; CFCs thin the ozone layer. Sustainable development meets today's needs without harming the ability of future generations to meet theirs, using clean energy, less waste and traditional knowledge.
- 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.
- Climate Change and the Greenhouse Effect – Climate is the average weather of a place over about 30 years. Greenhouse gases like carbon dioxide and methane trap some of the heat the Earth gives off. Humans have added a lot more of these gases by burning fossil fuels and cutting forests, so the Earth is warming. This causes melting ice, rising seas and more extreme weather. We can cut emissions (mitigation) and prepare for changes (adaptation).
- 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).
- Geographical Perspective on Selected Issues and Problems (Class 12) – Pollution means harmful things added to air, water, land or sound. Air pollution comes from burning fuel, factories and vehicles; water pollution from sewage, industry and farm chemicals; land pollution from garbage and chemicals; noise pollution from traffic and loudspeakers. Cities make huge amounts of solid waste that should be sorted, recycled and safely disposed. People move from villages to cities because of push factors (poverty, no work) and pull factors (jobs, services); many end up in slums with poor housing and services. Land degradation from erosion, waterlogging, salinity, mining and overgrazing can be healed, as shown by watershed work in Jhabua.
3. History of Earth and life
Geological time and dating · Major events in Earth history · Reading the geological record · History of life on Earth · Main taxonomic groups
- Evolution: How New Kinds of Living Things Arise – Variations arise during reproduction. Nature selects those that help survival, so over many generations populations change: this is evolution. Only inherited (DNA) changes pass on; acquired changes do not. Separated populations can become new species. Homologous organs, analogous organs and fossils help us trace who is related to whom, and complex organs evolved step by step.
- Biological Classification – Whittaker (1969) sorted living things into five kingdoms, Monera, Protista, Fungi, Plantae and Animalia, using cell type, cell wall, body plan, mode of nutrition, reproduction and relationships. Monera are prokaryotes (bacteria, archaebacteria, cyanobacteria, mycoplasma). Protista are one-celled eukaryotes in five groups. Fungi are heterotrophs with chitin walls in four classes. Lichens are an alga and a fungus living together. Viruses, viroids and prions are not placed in any kingdom.
4. Earth dynamics and composition
The atmosphere · The hydrosphere · The geosphere · Internal processes and plate tectonics · External geological processes · Soil formation · Natural hazards · Classifying rocks and the rock cycle · Mineral classification · Uses of minerals and rocks · Geological heritage
- Composition and Structure of the Atmosphere – The atmosphere is a thick blanket of air held to the Earth by gravity. It is mostly nitrogen (78%) and oxygen (21%), with small amounts of argon, carbon dioxide, ozone, water vapour and dust. It has five layers: troposphere (where weather happens), stratosphere (ozone layer), mesosphere (coldest), thermosphere (ionosphere, very hot) and exosphere (the outer edge). Weather is the state of air for a short time; climate is the average over about 30 years. Both are described by the same elements: temperature, pressure, wind, humidity, clouds and precipitation.
- Water in the Atmosphere – Air always holds some water as invisible vapour; the amount is called humidity. Absolute humidity is the actual mass of vapour in a volume of air; relative humidity is how full the air is compared with the most it could hold at that temperature. Water becomes vapour by evaporation (taking heat) and turns back to water by condensation (giving heat) when air cools to its dew point. Condensation near the ground gives dew, frost, mist and fog; higher up it gives clouds: cirrus, cumulus, stratus and nimbus. When drops or crystals grow heavy they fall as precipitation: rain, snow, sleet or hail. Rain forms in three main ways: convectional, orographic (relief) and cyclonic (frontal). Rainfall is heaviest near the equator and on windward coasts, and least in subtropical deserts, continental interiors and polar lands.
- Interior of the Earth: Earthquake Waves, Layers and Volcanoes – Nobody can dig to the centre of the Earth, so we learn about the inside from direct sources (mine rocks, deep drilling, lava) and indirect sources (heat and pressure with depth, meteors, gravity, magnetism and, above all, earthquake waves). P-waves travel through solids and liquids; S-waves only through solids. Where the waves do not arrive, we get shadow zones, which prove the outer core is liquid. Earthquakes are measured by magnitude (Richter) and intensity (Mercalli). The Earth has a thin crust, a thick mantle with a soft asthenosphere, a liquid outer core and a solid inner core. Magma that reaches the surface builds volcanoes; magma that cools inside forms intrusive landforms like batholiths, sills and dykes.
- Distribution of Oceans and Continents: Drift, Spreading and Plates – In 1912 Alfred Wegener said all continents were once one landmass, Pangaea, surrounded by one ocean, Panthalassa, and that they drifted apart. Matching coastlines, rocks, fossils, glacier deposits and placer gold supported him, but he could not explain the force. Mapping the ocean floor showed ridges, plains and trenches; Harry Hess then proposed sea-floor spreading: new crust forms at mid-ocean ridges and old crust sinks at trenches. This led to plate tectonics: the lithosphere is broken into rigid plates that move on the soft asthenosphere and meet at divergent, convergent and transform boundaries. The Indian plate broke away from the south, moved north, and collided with Asia to raise the Himalayas.
- Soil: How It Forms, Its Layers and How to Protect It – Soil is the thin, loose top layer of the land where plants grow. It is a mix of rock grains (about 45%), organic matter or humus (about 5%), water (about 25%) and air (about 25%). Soil forms very slowly when weathering breaks parent rock and living things add humus. Five factors control it: parent rock, climate, living things, relief (slope) and time. A cut through the ground shows layers called horizons: O (litter and humus), A (topsoil), B (subsoil, where washed-down minerals collect), C (broken rock) and R (bedrock). Soil texture depends on the share of sand, silt and clay. Soil feeds plants, stores and cleans water, stores carbon and is home to countless organisms, but erosion, salt and pollution can destroy it far faster than it forms.
- Natural Hazards – A natural hazard is a natural event that can harm people and property, such as an earthquake, volcano, landslide, flood, drought or cyclone. It becomes a disaster when it hits people who are not ready. Geological hazards come from inside the Earth; meteorological (weather) hazards come from the air and water. Risk = hazard × vulnerability ÷ capacity to cope, so warning systems, strong buildings and trained people cut the damage.
- Rocks and Minerals – A mineral is a natural, non-living solid with a fixed chemical make-up and a regular crystal shape, like quartz or halite. A rock is a mixture of one or more minerals. Rocks are of three types: igneous (from cooled magma or lava), sedimentary (from layers of pressed bits) and metamorphic (changed by heat and pressure). The rock cycle slowly turns each type into the others over millions of years.
- Mineral and Energy Resources of India (Class 12) – Minerals are natural substances with a fixed make-up. Most of India's minerals lie in old plateau rocks, in three belts: the north-eastern plateau, the south-western plateau and the north-western belt. Metallic minerals include iron ore, manganese, bauxite and copper; mica is a non-metallic mineral. Coal, petroleum and natural gas are conventional energy that will run out. Nuclear, solar, wind, tidal, geothermal and bio-energy are non-conventional and cleaner. Because minerals are non-renewable, we must use less, recycle scrap and use substitutes.
- Cultural Heritage – Cultural heritage is everything a community receives from the past, values today and wants to pass on: buildings and monuments, objects in museums, languages, music, dance, festivals, crafts, food and knowledge. Tangible heritage can be touched (immovable like temples and bridges, movable like coins and manuscripts); intangible heritage is lived and practised; natural heritage covers special landscapes and wildlife. Heritage gives identity, teaches history, brings income through tourism and links people across cultures. It is threatened by weathering, pollution, crowds, careless development, neglect and conflict, and is protected by conservation, laws, museums, heritage lists, education and local communities.
5. Animal physiology and histology
Animal nutrition · Animal coordination · Animal reproduction
- Life Processes and Photosynthesis – Life processes are the jobs every living body must keep doing to stay alive: nutrition, respiration, transport and excretion. Green plants do nutrition by photosynthesis: using sunlight and chlorophyll, they turn carbon dioxide and water into glucose and give out oxygen.
- Nervous System, Reflex Action and the Human Brain – Nerve cells (neurons) carry messages as electric impulses and pass them to the next cell with chemicals across a gap called a synapse. Quick safety responses (reflexes) are handled by the spinal cord; thinking and control come from the brain, which is guarded by the skull and a fluid cushion.
- Reproduction in Animals – Animals make young in two ways. In asexual reproduction one parent makes copies of itself (budding in hydra, splitting, regrowing from a piece, or eggs that need no male). In sexual reproduction a male gamete (sperm) joins a female gamete (egg) to make a zygote; this mixes genes and gives variation. Fertilisation can happen outside the body in water (frogs, most fish) or inside the body (insects, reptiles, birds, mammals). Land animals lay shelled eggs with membranes, or keep the young inside. After hatching, many animals change shape: complete metamorphosis (egg, larva, pupa, adult) or incomplete metamorphosis (egg, nymph, adult).
6. Plant physiology and histology
Photosynthesis · Xylem and phloem sap · Plant responses and hormones · Plant reproduction · Plant adaptations
- Life Processes and Photosynthesis – Life processes are the jobs every living body must keep doing to stay alive: nutrition, respiration, transport and excretion. Green plants do nutrition by photosynthesis: using sunlight and chlorophyll, they turn carbon dioxide and water into glucose and give out oxygen.
- How a Flowering Plant Works – A flowering plant cannot move, so it is built to collect: roots with millions of hairs take water and minerals from the soil, and wide leaves take carbon dioxide and light. Xylem carries raw sap (water + minerals) up, pulled by evaporation from leaves. Phloem carries elaborated sap (sugars) from leaves to roots, fruits and growing tips. Hormones control growth, chemical and physical defences protect it, and its shape changes with the environment.
- Coordination in Plants: Tropic Movements and Plant Hormones – Plants have no nerves or muscles, yet they respond. Some responses are quick and do not involve growth (touch-me-not leaves fold by moving water). Others are slow, directional growth movements called tropisms, controlled by plant hormones such as auxin, gibberellin, cytokinin and abscisic acid.
- Sexual Reproduction in Flowering Plants – A flower is the sex organ of a plant. The stamen makes pollen grains (male gametophytes). The ovule holds the embryo sac (female gametophyte, 7 cells, 8 nuclei). Pollination brings pollen to the stigma; the pistil checks it; a pollen tube carries two male gametes to the embryo sac. One fuses with the egg (zygote, 2n) and the other with two polar nuclei (primary endosperm nucleus, 3n). This is double fertilisation. The ovule becomes the seed and the ovary becomes the fruit.
7. Microorganisms and acellular forms
Bacteria and archaea · Bacterial metabolism · Microbes and infectious disease · Culturing microorganisms · Horizontal gene transfer · Viruses, viroids and prions
- Bacteria: Tiny Cells That Run the Planet – Bacteria are single-celled prokaryotes: they have no nucleus and no membrane-bound organelles. Their DNA is one circular loop (the nucleoid), often with small extra rings called plasmids. They have 70S ribosomes, a cell membrane, a cell wall of peptidoglycan, and may have a capsule, pili and flagella. Shapes: coccus, bacillus, spirillum, vibrio. They reproduce by binary fission and can swap genes sideways by conjugation, transformation and transduction. They feed by photosynthesis, chemosynthesis, decomposition, symbiosis or parasitism, and drive the carbon and nitrogen cycles. Archaea look similar but differ in wall and membrane chemistry and often live in extreme places.
- 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.
- Microbial Culture: How to Grow Microbes in a Lab – To study a microbe, we grow lots of it from a few cells. This is a culture. First we kill every germ on tools and food (sterilisation). Then we give the microbes food in a dish (a culture medium). We spread a few cells with a hot-then-cooled wire loop (streaking) and keep the dish warm. Each cell becomes a dot we can see, called a colony. In a flask, the number of cells grows in four phases: lag, log, stationary and death.