Ukraine 10 клас Biology and Ecology
Chapters: 5
1. Introduction
Biology, ecology and life
- Systems Thinking: Seeing the Whole, Not Just the Parts – A system is a set of parts that are linked and work together for a purpose. It has a boundary, takes inputs from its environment and gives outputs. A system can do things none of its parts can do alone. Changing one part changes others, often through feedback loops. Life is organised as systems inside systems, from cells to the biosphere. Systems thinking helps us analyse, design and optimise systems, and plan sustainable development.
2. Biodiversity
Systematics · Viruses, viroids, prions · Prokaryotes and eukaryotes
- The Living World – Earth has millions of kinds of living things; this variety is biodiversity. To study them we sort them into groups. Taxonomy is naming, describing and classifying; systematics also asks how groups are related. All life falls in three domains: Bacteria, Archaea and Eukarya. Organisms are placed in 7 main ranks, from kingdom down to species, and each species gets a two-part Latin name like Mangifera indica.
- 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.
- Cell: The Unit of Life – Every living thing is made of cells, and every new cell comes from an old cell. Prokaryotic cells (bacteria) have no nuclear envelope and no membrane-bound organelles; eukaryotic cells have a true nucleus and many organelles. The membrane is a fluid mosaic of lipids and proteins; plants add a cellulose wall. ER, Golgi, lysosomes and vacuoles form the endomembrane system. Mitochondria and plastids make energy and food, ribosomes make proteins, the cytoskeleton, cilia, flagella and centrioles give shape and movement, and the nucleus holds the DNA.
3. Metabolism and energy
Biomolecules and metabolism · Metabolism and health
- Biomolecules – A cell is mostly water, plus four big families of carbon compounds: proteins, carbohydrates, lipids and nucleic acids. Grinding tissue in acid separates small molecules (acid-soluble pool) from big ones – proteins, polysaccharides and nucleic acids (acid-insoluble pool). Proteins are chains of amino acids folded into four levels of structure. Polysaccharides are chains of sugars; lipids are fatty acids on glycerol; nucleic acids are chains of nucleotides. Enzymes are protein catalysts that bind a substrate at the active site, lower the activation energy, and are affected by temperature, pH, substrate level and inhibitors.
- Nutrition – Nutrition is how we get and use the substances in food. The body needs six groups of nutrients: carbohydrates and fats (mainly energy), proteins (growth and repair), vitamins and minerals (small amounts to keep the body working), and water, plus fibre for healthy digestion. Carbohydrate and protein give about 17 kJ per gram, fat about 37 kJ per gram. A balanced diet gives all nutrients in the right amounts, and energy in should roughly equal energy out.
4. Heredity and variation
Laws of heredity · Genome organisation · Variation and mutations · Medical genetics
- Heredity and Mendel's Laws – Heredity is the passing of traits from parents to children through genes. Each parent gives one copy of every gene. A dominant copy hides a recessive one, which is why Mendel saw 3:1 in a monohybrid cross and 9:3:3:1 in a dihybrid cross. Genes are pieces of DNA that make proteins, and proteins build the trait.
- Gene Regulation: How Cells Switch Genes On and Off – Every cell carries the same DNA but uses only some genes. Cells control mostly at transcription. In bacteria, the lac operon is a set of genes under one promoter and one operator: a repressor blocks it when there is no lactose; lactose removes the repressor and the genes are read (an inducible operon). In eukaryotes, transcription factors, enhancers and silencers control each gene, and epigenetic marks (DNA methylation, histone packing) can keep genes off without changing the DNA code. Different on/off patterns make different cell types (differentiation).
- Mutations – A mutation is a sudden, lasting change in the DNA. Gene (point) mutations change one or a few bases: substitution, insertion or deletion. Insertions and deletions shift the reading frame. Chromosome mutations change big pieces or the number of chromosomes. Mutations happen by chance or because of mutagens such as UV light, X-rays and some chemicals. They can be harmful, neutral or useful, and they are the first source of all genetic variation.
- Genetic Disorders – A genetic disorder is a health problem caused by a change in a gene or in the number or shape of chromosomes. Single-gene disorders can be recessive (cystic fibrosis, sickle cell anaemia: you need two faulty copies), dominant (Huntington disease: one faulty copy is enough) or X-linked (haemophilia, colour blindness: mostly boys). Chromosome disorders such as Down syndrome (an extra chromosome 21) come from a mistake when egg or sperm cells form. Punnett squares predict the chance of each outcome, and genetic testing, counselling and gene therapy help families.
5. Reproduction and development
Regeneration and cell life · Human reproduction
- Cell Cycle and Cell Division – A cell grows, copies its DNA and splits in a fixed order called the cell cycle: interphase (G1, S, G2) and M phase. In S phase the DNA doubles (2C → 4C) but the chromosome number stays the same. Mitosis (prophase, metaphase, anaphase, telophase) and cytokinesis give two cells identical to the parent – it is an equational division used for growth and repair. Meiosis has two divisions; in meiosis I homologous chromosomes pair, cross over and separate, halving the chromosome number (2n → n). It makes four haploid cells for gametes and creates variation.
- Reproduction in Human Beings and Reproductive Health – At puberty, hormones from the brain make the testes and ovaries start working. The male system makes and carries sperm; the female system makes eggs and provides a place (uterus) where a baby develops. Fertilisation happens in the oviduct, and the embryo is fed through the placenta. Reproductive health includes safe choices, contraception, avoiding female foeticide, and preventing sexually transmitted diseases such as HIV/AIDS.