Biology 2 (Grade 11: 2-1, 2-2, 2-3)
Vertebrates and plants, the cell and its energy, human body systems, immunity, cell division, Mendelian and complex inheritance, and molecular genetics.
Vertebrates and plants, the cell and its energy, human body systems, immunity, cell division, Mendelian and complex inheritance, and molecular genetics.
Units of the book
| Unit | What to know |
|---|---|
| 2-1: Vertebrates and plants | echinoderms, chordates, fish, amphibians, reptiles, birds, mammals; plants, their tissues, hormones and reproduction |
| 2-1: The cell and its energy | organelles, membrane transport, biomolecules, photosynthesis and respiration |
| 2-2: Body systems | skeletal and muscular, nervous, circulation, breathing and excretion, digestion and hormones, reproduction, immunity |
| 2-2 and 2-3: Division and heredity | the cell cycle, mitosis and meiosis, Mendelian and sex-linked inheritance, DNA and replication, transcription, translation, mutations |
| Animal behaviour | innate and learned behaviour, habituation, imprinting, conditioning, communication and altruism |
Facts to remember
- A–T (2), G–C (3): base pairing (bonds)
- RNA: T → U: RNA
- Aa × Aa ⇒ 3: 1: monohybrid (phenotype)
- AaBb × AaBb ⇒ 9: 3: 3: 1: dihybrid
- 2n = 46 ⇒ n = 23: humans
- mitosis ⇒ 2 cells, meiosis ⇒ 4: cell division
- codon = 3 bases: genetic code
🧠 Memory kit: vertebrates and plants
| Topic | What to know |
|---|---|
| Chordate features | notochord, dorsal hollow nerve cord, pharyngeal pouches, a tail beyond the anus (at some stage of life). |
| Echinoderms | sea stars and urchins: a water vascular system, tube feet and five-part symmetry. |
| Heart chambers | fish 2, amphibians 3, reptiles 3 (crocodiles 4), birds 4, mammals 4. |
| Fish and amphibians | fish: gills, lateral line, fins. Amphibians: breathe through skin and lungs, go through metamorphosis (tadpole → frog), lay eggs without shells. |
| Reptiles and birds | reptiles: dry scales and shelled amniotic eggs laid on land. Birds: feathers, hollow bones, air sacs, warm-blooded. |
| Mammals | hair and milk glands. Monotremes lay eggs (platypus), marsupials have pouches (kangaroo), placentals grow young inside the uterus. |
| Plant groups | mosses: non-vascular. Ferns: vascular, no seeds (spores). Gymnosperms: naked seeds in cones (pine). Angiosperms: flowers and fruit. |
| Monocots vs dicots | monocots: one seed leaf, parallel veins, flower parts in 3s, scattered bundles, fibrous roots. Dicots: net veins, parts in 4s or 5s, bundles in a ring, a tap root. |
| Transport tissues | xylem carries water and minerals up (dead cells). Phloem carries food (sugar) both ways (living cells). |
| Plant hormones | auxin: bending to light and apical dominance. Gibberellin: stem growth and germination. Cytokinin: cell division. Ethylene: fruit ripening. Abscisic acid: dormancy and closing stomata. |
| Parts of a flower | male: stamen (anther + filament). Female: carpel or pistil (stigma + style + ovary). Angiosperms have double fertilization. |
🧠 Memory kit: the cell and its energy
| Organelle or process | Its job and what to know |
|---|---|
| Nucleus | the control centre; holds the DNA. |
| Mitochondria | “the powerhouse”: cellular respiration, making ATP. |
| Chloroplasts | photosynthesis (plants and algae only). |
| Ribosomes | make proteins. |
| Endoplasmic reticulum | rough (with ribosomes) for proteins; smooth for lipids. |
| Golgi apparatus | “the post office”: modifies, packs and ships proteins. |
| Lysosomes | digest waste and worn-out parts (animal cells). |
| Vacuole and wall | plants: one large central vacuole and a cellulose wall. Animals: small vacuoles, no wall. |
| Cell membrane | a phospholipid bilayer (fluid mosaic model), selectively permeable. |
| Passive transport | diffusion: high to low concentration, no energy. Osmosis: water crossing a membrane. Facilitated diffusion: through a carrier protein, no energy. |
| Active transport | low to high concentration, needs ATP; endocytosis and exocytosis move big particles. |
| Solutions | hypertonic → the cell shrinks. Hypotonic → it swells (an animal cell may burst; a plant cell becomes firm). Isotonic → no change. |
| Photosynthesis | 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Light reactions in the thylakoids (ATP, NADPH, O₂ released); the Calvin cycle in the stroma (fixes CO₂). |
| Cellular respiration | C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP. Glycolysis in the cytoplasm (2 ATP), then the Krebs cycle in the matrix, then the electron transport chain (most ATP); about 36–38 ATP in all. |
| Fermentation | without oxygen: lactic acid in muscles (sore muscles), alcoholic in yeast (ethanol + CO₂). |
🧠 Memory kit: body systems
| Topic | What to know |
|---|---|
| Skeleton and muscles | 206 bones in an adult. Muscles: skeletal (voluntary, striped), smooth (involuntary, in organs), cardiac (involuntary, striped). |
| Nervous system | a neuron: dendrites → cell body → axon. Cerebrum: thinking; cerebellum: balance and coordination; medulla: breathing and heart rate. |
| Circulation | arteries leave the heart, veins return to it, capillaries exchange. Exception: the pulmonary artery carries deoxygenated blood and the pulmonary vein oxygenated blood. |
| Blood | red cells (haemoglobin carries O₂), white cells (defence), platelets (clotting), plasma (the liquid). |
| Blood groups | A: A antigens, anti-B antibodies. B: the reverse. AB: no antibodies → universal recipient. O: no antigens → universal donor. |
| Breathing and excretion | gas exchange in the alveoli; the diaphragm contracts to breathe in. The kidney’s unit is the nephron: filtration (glomerulus and Bowman’s capsule) → reabsorption → secretion. The liver makes urea. |
| Digestion | mouth: amylase starts on starch. Stomach: pepsin and acid for protein. Small intestine: most digestion and absorption (villi); bile from the liver emulsifies fat; the pancreas sends lipase, trypsin and amylase. Large intestine: absorbs water. |
| Endocrine glands | pituitary: the master gland, growth hormone. Thyroid: thyroxine (metabolism). Parathyroid: calcium. Adrenal: adrenaline. Pancreas: insulin lowers blood sugar, glucagon raises it. |
| Immunity | non-specific: skin, fever, phagocytes. Specific: B cells make antibodies; helper and killer T cells. A vaccine → active immunity. HIV attacks helper T cells. |
🧠 Memory kit: genetics and behaviour
| Topic | What to know |
|---|---|
| Mendel’s terms | dominant (capital) and recessive (small); homozygous AA or aa, heterozygous Aa; genotype = the letters, phenotype = what you see. |
| Cross ratios | Aa × Aa → 1: 2: 1 genotypes, 3: 1 phenotypes. Aa × aa → 1: 1 (test cross). AaBb × AaBb → 9: 3: 3: 1. |
| Incomplete and co-dominance | incomplete: a blend (red × white → pink). Co-dominance: both show (blood group AB, roan cattle). |
| Sex-linked traits | colour blindness and haemophilia are on the X; more common in males (XY) with one X, and a son inherits it from his mother. |
| Chromosome disorders | Down: three copies of chromosome 21. Turner: XO (female). Klinefelter: XXY (male). |
| DNA | a double helix (Watson and Crick, using Rosalind Franklin’s X-ray images). A–T (2 bonds) and G–C (3). Replication is semi-conservative. |
| Gene to protein | transcription: DNA → mRNA in the nucleus (U instead of T). Translation: mRNA → protein at the ribosome. A codon is 3 bases; 64 codons; start codon AUG. |
| Cell division | mitosis: prophase → metaphase → anaphase → telophase → 2 identical cells (2n). Meiosis: 4 different haploid cells (n), crossing over in prophase I. |
| Innate behaviour | inherited, not learned: reflexes, instincts (nest building), migration, hibernation (winter), estivation (summer). |
| Learned behaviour | habituation: stops reacting to a harmless repeated stimulus. Imprinting: the young follow the first moving thing they see (Lorenz’s geese). Classical conditioning: linking two stimuli (Pavlov’s dog). Operant conditioning: trial and error with a reward (Skinner). Insight: solving a new problem from past experience (the highest form). |
| Communication and altruism | pheromones are chemical messages. A bee’s round dance → food is near; the waggle dance → far. Altruism: helping others at a cost to oneself. |
- Mitosis phases: PMAT, “Please Make Another Tea” = prophase, metaphase, anaphase, telophase.
- Arteries and veins: Artery = Away from the heart; veins visit it again.
- Xylem and phloem: “xylem drinks (water), phloem feeds (food)”.
- Base pairs: “Apple in the Tree, Car in the Garage” (A–T, C–G). In RNA, U replaces T.
- Photosynthesis and respiration are mirror images: the same equation both ways; one stores energy in glucose, the other releases it as ATP.
A way of memorizing that sticks
- Understand before you memorize: read “in plain words” for each formula and say out loud what it measures and why each quantity is multiplied or divided. A formula you understand takes a minute to learn.
- Active recall: cover the formula column and write it from memory, then check. Writing from memory beats rereading by far.
- Spaced repetition: review the same sheet after 1 day, 3 days, a week and two weeks. Four short reviews lock it in until test day.
- Your own formula page: write every formula of a book on one page by hand. If it does not fit, you are writing things you can derive, so cut them.
- Teach it: explain the formula to a friend, or to yourself in a mirror, in two sentences. If you cannot explain it, you do not know it yet.
- Use it at once: after each group, press “Try one” in the patterns below. Memory sets when you use it.
Question patterns
Vertebrates
Identify each class: feathers, hair, scales, 3- or 4-chambered heart.
Plants and tissues
Xylem carries water up; phloem carries food.
Plant hormones and tropisms
Auxin for light, ethylene for ripening.
Flowers and fertilization
The ovary becomes the fruit, the ovule the seed.
Organelles
Mitochondria for energy, ribosomes for protein, Golgi for packaging.
Membrane transport
Only active transport needs energy.
Biomolecules
An enzyme is a protein that lowers activation energy.
Photosynthesis and respiration
Light reactions in the thylakoid, Calvin in the stroma, Krebs in the matrix.
Skeleton and muscles
Ball-and-socket for shoulder and hip; hinge for elbow and knee.
Nerves and senses
Cerebellum for balance; medulla for breathing.
Circulation, breathing, excretion
Arteries leave the heart; veins return to it.
Digestion, glands, vitamins
Insulin lowers glucose; glucagon raises it.
Reproduction and immunity
B cells make antibodies; HIV attacks helper T cells.
The cell cycle
Chromosomes line up in metaphase.
Chromosome counts
Gametes have half the number.
Mendelian genetics
Draw a Punnett square.
Sex-linked inheritance
A son gets his X from his mother.
DNA and RNA
A–T, G–C; RNA uses U for T.
Blood groups
| Type | Antigen on cells | Antibodies in plasma |
|---|---|---|
| A | A | anti-B |
| B | B | anti-A |
| AB | A and B | none (universal recipient) |
| O | none (universal donor) | anti-A + anti-B |
Kinds of behaviour
| Type | Example |
|---|---|
| imprinting | ducklings follow the first moving object |
| habituation | horses ignore crowd noise |
| classical conditioning | Pavlov’s dog and the bell |
| operant conditioning | a rat presses a lever for food |
| insight | a crow uses cars to crack nuts |
| altruism | a warning call that risks the caller |
More patterns (figures and calculations)
Blood groups
O is the universal donor; AB the universal recipient.
Types of behaviour
Is it inherited or learned? Then, how was it learned?
Genetics and chromosome disorders
Klinefelter XXY, Turner XO, Down: three copies of 21.