Cambridge IGCSE Biology

Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition

Mrs. Gren

Movement

An action by an organism or part of an organism causing a change of position or place

Respiration

The chemical reactions in cells that break down nutrient molecules and release energy for metabolism

Sensitivity

The ability to defect or sense stimuli in the internal or external environment and to make appropriate responses

Growth

A permanent increase in size and dry mass by an increase in cell number or cell size or both

Excretion

Removal from organisms of the waste products of metabolism (chemical reactions in cells including respiration), toxic materials and substances in excess of requirements

Nutrition

Taking in of materials for energy, growth and development; plants require light, carbon dioxide, water and ions; animals need organic compounds and ions and usually need water

Common ancestor

A species that lived long ago that is thought to be a distant ancestor of two or more species living today

Organism

A living thing

Morphology

The overall form and shape of organisms' bodies, such as whether they had legs or wings

Anatomy

The detailed body structure of an organism

Kingdom, Phylum, Class, Order, Family, Genus, Species

The classification system

The binomial naming system

An internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and species created by Linnaeus

Animals, Plants, Fungi, Protoctista, Prokaryotes, (Viruses)

The kingdoms of living organisms

Animals

Multicellular (their bodies contain many cells); cells have a nucleus, but no cell walls or chloroplasts; feed on organic substances made by other living organisms

Plants

Multicellular; cells have a nucleus, cell walls made of cellulose and often contain chloroplasts; feed by photosynthesis; may have roots, stems and leaves

Fungi

Usually multicellular; have nuclei; have cell walls, not made of cellulose; do not have chlorophyll; feed by saprophytic or parasitic nutrition

Protoctista

Multicellular or unicellular; cells have a nucleus; cells may or may not have a cell wall and chloroplasts; some feed by photosynthesis and others feed on organic substances made by other organisms

Prokaryotes

Often unicellular (single-celled); have no nucleus; have cell walls, not made of cellulose; have no mitochondria

Viruses

Not considered a living thing because they cannot move, show sensitivity, grow, reproduce, excrete or feed

Phylum Vertebrates, Phylum Invertebrates

Animal classification - Phylums

Phylum Vertebrates

Have backbones; Class Fish; Class Amphibians; Class Reptiles; Class Birds; Class Mammals

Several pairs of jointed legs; exoskeleton; insects; crustacean; arachnids; myriapods

Phylum Invertebrates

Class Fish

Vertebrates with scaly skin; have gills; have fins

Class Amphibians

Vertebrates with moist, scale-less skin; eggs laid in water, larva (tadpole) lives in water; adult often lives on land; larva has gills; adult has lungs

Class Reptiles

Vertebrates with scaly skin; lay eggs with rubbery shells

Class Birds

Vertebrates with feathers; forelimbs have become wings; lay eggs with hard shells; endothermic; have a beak; heart has four chambers

Class Mammals

Vertebrates with hair; have a placenta; young feed on milk from mammary glands; endothermic; have a diaphragm; heart has four chambers; have different types of teeth (incisors; canines; premolars and molars)

Insects

Arthropods with three pairs of jointed legs; two pairs of wings (one or both may be vestigial); breathe through trachea; body divided into head, thorax and abdomen

Crustaceans

Arthropods with more than four pairs of jointed legs; not millipedes or centipedes; breathe through gills

Arachnids

Arthropods with four pairs of jointed legs; breathe through gills called book lungs

Myriapods

Body consists of many segments; each segment has jointed legs

Ferns and flowering plants

Plant classification

Ferns

Plants with roots, stems and leaves; have leaves called fronds; do not produce flowers; reproduce by spores

Flowering plants

Plants with roots, stems and leaves; reproduce sexually by means flowers and seeds; seeds are produced inside the ovary, in the flower; divided into monocotyledonous and dicotyledonous (monocots and dicots)

Monocotyledonous plants (monocots)

Have only one cotyledon in their seeds; have a branching root system; often have leaves in which the veins run parallel to one another

Dicotyledonous plants (dicots)

Have two cotyledons in their seeds; frequently have a tap root system; leaves are often broader than monocots'; have a network of branching veins

Light microscope

A microscope that uses light to produce images; can magnify 1500 times

Electron microscope

Uses beams of electrons; can magnify 500,000 times

Photomicrograph

A picture made using a microscope

Cell membrane

A very thin layer of protein and fat; controls what goes in and out of the cell; partially permeable

Partially permeable

Lets some substances through but not others

Cell wall

In plants is made of cellulose; helps to protect and support the cell; fully permeable

Fully permeable

Able to let most substances pass through

Cytoplasm

Jelly-like material found in cells; nearly all water; contains many substances, especially proteins; where metabolic reactions take place

Vacuole

A space in a cell, surrounded by a membrane, and containing a solution; in plant cells are very large and contain cell sap; in animal cells are much smaller called vesicle

Cell sap

A solution of sugars and other substance inside the vacuole of a plant cell

Vesicles

Hundreds of tiny vacuoles, each contain a chemical, called a transmitter substance or neurotransmitter

Chloroplasts

An organelle found in some plant cells, which contains chlorophyll and where photosynthesis takes place; in plant cells often contain starch grains

Chlorophyll

A green, light-absorbing pigment found inside chloroplasts in plant cells; used for making food for the plant by photosynthesis

Nucleus

Where the genetic information is stored, kept on chromosomes; helps the cell to make the right sorts of proteins

Chromosome

A thread-like structure of DNA, made up of a string of genes; very long and thin, cannot be seen using the electron microscope; when the cell divides, becomes short and thick, and can be seen with a good light microscope

Mitochondrion (mitochondria)

The powerhouse of the cell; organelles in which aerobic respiration takes place, releasing energy for use by the cell; found a lot in muscle cells and sperm cells; found in all cells except prokaryotes

Ribosome

Tiny organelles where protein synthesis takes place; attached to the rough endoplasmic reticulum; scattered freely in the cytoplasm; found in all types of cells

Micrometer

1 m = 10^6 μm

Real size formula

Real size in μm = size of the image in μm / magnification

Tissue

A group of cells with similar structures, working together to perform a shared function

Organ

A structure made up of a group of tissues, working together to perform specific functions

Organ system

A group of organs with related functions, working together to perform body functions

Diffusion

The net movement of molecules and ions from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement

Osmosis

The diffusion of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane

Animal cell in a hypotonic (dilute) solution

The cell swells as more and more water enters. The cell membrane stretches until eventually the strain is too much, and the cell bursts.

Animal cell in a hypertonic (concentrated) solution

The cytoplasm shrinks as water goes out through the cell membrane. The cell shrivels up.

Plant cell in a hypotonic (dilute) solution

The cell becomes turgid and does not burst because of their fully-permeable cell wall.

Plant cell in a hypertonic (concentrated) solution

The cell becomes flaccid as the cytoplasm shrinks and stops pushing outwards on the cell wall.

Plant cell in an extremely hypertonic (concentrated) solution

The cell becomes plasmolysed as the cytoplasm and cell membrane shrinks further and further away from the cell wall, leaving the cell wall behind.

Active transport

The movement of molecules and ions in or out of a cell through the cell membrane, from a region of their lower concentration to a region their higher concentration against a concentration gradient, using energy released during respiration

Water

An important solvent: If their cells dry out, the reactions stop, and the organism dies.

Carbohydrates

Contain carbon (C), hydrogen (H), and oxygen (O); divided into monosaccharides, disaccharides, and polysaccharides

Monosaccharides (simple sugars)

Are very small, soluble, and taste sweet; e.g. glucose (C6H12O6)

Disaccharides

A carbohydrate whose molecules are made of two monosaccharide molecules; soluble and taste sweet; e.g. sucrose and maltose

Polysaccharides

Many monosaccharides joined together; insoluble and don't taste sweet; e.g. cellulose and starch

Carbohydrates (functions)

Energy production; respiration through glucose; transportation through sucrose; plants' energy storage through starch; animals' energy storage through glycogen; plants' cell walls made of cellulose

Testing for carbohydrates

Add Benedict's solution and heat; Blue - green - yellow - orange - brick red

Fats (lipids)

Contain carbon (C), hydrogen (H), and oxygen (O); made of glycerol and fatty acids; insoluble; called oils at room temperature

Fats (functions)

Energy storage, insulates mammals' heat through adipose tissue

Testing for fats and oils

Ethanol emulsion test; layer of emulsion (white and opaque, like milk) apparent

Proteins

Contain carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and some sulfur (S); monomers are amino acids

Proteins (functions)

Making new cells, growth, repairing damaged parts of the bod, make antibodies

Testing for proteins

Biuret test; blue (none) - purple (present)

DNA (deoxyribonucleic acid)

The chemical that makes up genes and chromosomes; inherited from parents; double helix

DNA bases

A-T and C-G; provide the kinds of proteins made, determines how cells, tissues, and organs develop

Catalyst

A substance that increases the rate of a chemical reaction and is not changed by the reaction

Enzymes

Proteins that function as biological catalysts

Metabolic reactions

Chemical reactions taking place within any living organism

The lock and key mechanism

The enzyme is like a clock, into which the substrate fits like a key.

Substrate

The substance on which an enzyme acts

Product

The substance formed in an enzyme-controlled reaction

Enzyme-controlled reaction

The substrate fits into the complimentary enzyme's active site, forming an enzyme-substrate complex. The enzyme then breaks the substrate apart.

Temperature and enzyme activity

At higher temperatures, more kinetic energy is generated. This results in more collisions and collisions with more energy, creating more enzyme-substrate complexes. At too high temperature (40°C upwards), the enzyme denatures. The temperature at which an enzyme works fastest is called its optimum temperature.

pH and enzyme activity

Most enzymes are their correct shapes at pH7. If the pH becomes too acidic or alkaline, they become denatured. Some enzymes (e.g. in the human stomach) work best at pH2.

Denatured

An enzyme is said to be denatured when its molecule has changed shape so much that the substrate can no longer fit into it

Inorganic substances

Substances not made by living things (e.g. carbon dioxide, water and minerals)

Organic substances

Substances made by living things, contain carbon, hydrogen and oxygen

Photosynthesis

The process by which plants manufacture carbohydrates from raw materials using energy from light

Photosynthesis equation

Carbon dioxide + water => (through sunlight and chlorophyll) glucose + oxygen

Lamina

A broad, flat part of the leaf, which is joined to the rest of the plant by a petiole

Petiole

A leaf stalk

Vascular bundles

A group of xylem vessels and phloem tubes; run through the petiole, which form the veins in the leaf; help to support the plant

Epidermis (plant)

A tissue made up of a single layer of cells which covers the top and bottom of a leaf, and the outside of the stem and root