biology mine igcse

• Movement


  Action by an organism or part of an organism causing a change of position or place
• Respiration


  Chemical reactions in cells that break down nutrient molecules and release energy for metabolism
• Sensitivity


  Ability to detect and respond to changes in the internal or external environment
• Reproduction


  Processes that make more of the same kind of organism
• Excretion


  Removal of the waste products of metabolism and substances in excess of requirements
• Nutrition


  Taking in of materials for energy, growth and development
• Organisms


  • Can be classified into groups by the features that they share
  • Species is a group of organisms that can reproduce to produce fertile offspring
• Binomial system of naming species


  Internationally agreed system in which the scientific name of an organism is made up of two parts showing the genus and species
• Classification systems aim to reflect evolutionary relationships
• The sequences of bases in DNA are used as a means of classification
• Groups of organisms which share a more recent ancestor (are more closely related) have base sequences in DNA that are more similar than those that share only a distant ancestor
• Five kingdoms


  • Animal kingdom
  • Plant kingdom
  • Fungus
  • Protoctista
  • Prokaryote
• Animal kingdom


  • Their cells have a nucleus, but no cell walls or chloroplasts
  • They feed on organic substances made by other living organisms
• Plant kingdom


  • Their cells have a nucleus and cell walls made of cellulose and often contain chloroplasts
  • They feed by photosynthesis
  • They may have roots, stems and leaves (but some plants do not have these organs)
• Fungus


  • They are usually multicellular (many-celled), but some such as yeast are unicellular (single-celled)
  • They have nuclei and cell walls, but the walls are not made of cellulose
  • They do not have chlorophyll
  • They feed by digesting waste organic material and absorbing it into their cells
• Protoctista


  • They are multicellular or unicellular
  • Their cells have a nucleus and may or may not have a cell wall and chloroplasts
  • Some feed by photosynthesis and others feed on organic substances made by other organisms
• Prokaryote


  • They are usually unicellular (single-celled)
  • They have no nucleus
  • They have cell walls, not made of cellulose
  • They have no mitochondria
  • They have a circular loop of DNA, which is free in the cytoplasm
  • They often have plasmids
• Vertebrates


  • Fish
  • Amphibians
  • Reptiles
  • Birds
  • Mammals
• Fish


  • They are vertebrates with scaly skin
  • They have gills throughout their life
  • They have fins
  • Their eggs have no shells and are laid in water
• Amphibians


  • They are vertebrates with skin with no scales
  • Their eggs have no shells and are laid in water
  • The tadpoles live in water, but adults often live on land
  • The tadpoles have gills for gas exchange, but adults have lungs
• Reptiles


  • They are vertebrates with scaly skin
  • They lay eggs with soft shells on land
• Birds


  • They have feathers (and also sometimes a few scales)
  • They have a beak
  • Their front two limbs are wings (though not all birds can fly)
  • They lay eggs with hard shells
• Mammals


  • They have hair on their skin
  • Their young develop in a uterus, attached to the mother by a placenta
  • The females have mammary glands, which produce milk to feed their young
  • They have different kinds of teeth (incisors, canines, premolars and molars)
  • They have a pinna (ear flap) on the outside of the body
  • They have sweat glands in the skin
  • They have a diaphragm
• Arthropods


  • Insects
  • Crustaceans
  • Arachnids
  • Myriapods
• Insects


  • They are arthropods with three pairs of jointed legs
  • They have two pairs of wings (one or both may be vestigial)
  • They have one pair of antennae
  • Their body is divided into a head, thorax and abdomen
  • They breathe through tubes called tracheae
• Crustaceans


  • They are arthropods with more than four pairs of jointed legs
  • They have two pairs of antennae
• Arachnids


  • They are arthropods with four pairs of jointed legs
  • They have no antennae
  • Their body is divided into two parts – a cephalothorax and abdomen
• Myriapods


  • Their body consists of many similar segments
  • Each of their body segments has jointed legs
  • They have one pair of antennae
• Ferns


  • They are plants with leaves called fronds
  • They do not produce flowers, but instead reproduce by means of spores produced on the underside of the fronds
  • They are plants with roots, stems and leaves (fronds)
• Flowering plants


  • They are plants with roots, stems and leaves
  • They reproduce using flowers and seeds
  • Their seeds are produced inside an ovary, in the flower
• Characteristic features of dicots

  • They have seeds with two cotyledons
  • They usually have a main root with side roots coming out from it
  • Their leaves have a network of veins
  • They have flower parts (e.g. petals) in multiples of four or five
  • They have vascular bundles in the stem, arranged in a ring
• Characteristic features of monocots


  • They have seeds with one cotyledon
  • Their roots grow out directly from the stem
  • Their leaves have parallel veins
  • They have flower parts in multiples of three
  • They have vascular bundles in the stem, arranged randomly
• Viruses


  They are not living. They have a protein coat and genetic material inside without nucleus.
• Cell structure


  • Cytoplasm is found inside the cell and contains all the other cell structures
  • The large nucleus is surrounded by a nuclear membrane to separate it from the cytoplasm
  • The cell membrane surrounds the cell
  • The cell wall is made of cellulose and surrounds the cell membrane in plant cells
  • Chloroplasts are organelles found in the cytoplasm that are packed with the pigment chlorophyll and so are green in colour
  • Vacuoles are large vesicles that take up a large part of the interior of plant cell
  • Mitochondria (singular: mitochondrion) are organelles found throughout the cytoplasm
  • Ribosomes are tiny structures that can be free within the cytoplasm or attached to a system of membranes within the cell known as Endoplasmic Reticulum
  • Endoplasmic reticulum studded with ribosomes looks rough under the microscope; this gives rise to its name of Rough Endoplasmic Reticulum (R.E.R.)
  • Vesicles can also be seen using a higher magnification – these are small circular structures found moving throughout the cytoplasm
• Nucleus


  Contains genetic material in chromosomes which control how cells grow and work and control cell division
• Cytoplasm


  Supports cell structures, site of many chemical reactions, contains water and many solute
• Cell membrane


  Holds the cell together, controls substances entering and leaving the cell
• Cell wall


  Gives the cell extra support and defines its shape
• Chloroplast


  Site of photosynthesis, providing food for plants, the chlorophyll pigments absorb light energy needed for the reaction to occur
• Vacuoles


  Contains cell sap, used for storage of certain materials, also helps support the shape of the cell