Unit 1: Characteristics and classification of living organisms
List and describe the characteristics of living organisms
MRS GREN
Movement
an action by an organism or part of an organism causing a change of position or place
Respiration
a complex series of reactions taking place in all living cells that break down nutrients molecules to release energy from food
Sensitivity
the ability to detect changes in the environment (stimuli) and make responses
Growth
a permanent increase in size and dry mass by an increase in cell number or cell size or both
Reproduction
processes that make more of the same kind of organism
Excretion
the removal from organisms of toxic materials, the waste products of metabolism and substances in excess requirements
Nutrition
taking in of nutrients which are organic substances and mineral ions, containing raw materials or energy for growth and tissue repair, absorbing and assimilating them
Describe how to use the binomial system to name organisms
the binomial system uses 2 names for each species
Genus
Trivial
Name a scientific name of an organism using the binomial system
Homo sapiens: human
Panthera leo: lion
Canis lupus: wolf
List the external features of nematodes, annelids and molluscs
Nematodes
Have thread-like bodies that taper at mouth and anus. Bodies are not made up of segments
Annelids
Bodies are made up of segments. Some have paddle-like extensions for moving: chaetae or bristles
Molluscs
Bodies are not made up of segments. Have a muscular 'foot' for burrowing or movement. Many have 1 or 2 shells for protection
List the external features of arthropods
Arthropods are segmented animals with jointed legs and an exoskeleton
List the external features of four classes of arthropod: insects, crustaceans, arachnids and myriapods
Myriapods
Long bodies made up of segments. Not divided into separate regions. Centipedes: 1 pair of legs per segment (and can paralyse prey). Millipedes: 2 pairs of legs per segment.
Insects
Bodies divided into 3 parts: head, thorax and abdomen. 3 pairs of legs on thorax. 1 pair of antennae on head and compound eyes. Breathe through spiracles (holes in side of thorax and abdomen) Covered by a waterproof cuticle.
Crustaceans
Bodies divided into a cephalothorax (head-thorax) and abdomen. Chalky exoskeleton. 2 pairs of antennae and compound eyes. Between 5 and 20 pairs of legs. Breathe using gills.
Arachnids
Bodies divided into 2 parts: cephalothorax and abdomen. 4 pairs of legs. (Poison fangs). No wings. No antennae. Several pairs of simple, not compound eyes. Spinnerets (weave silken webs).
Define the term vertebrate
Vertebrates are animals that have a vertebral column or backbone
List the main features of the following vertebrate groups: fish, amphibians, reptiles, birds and mammals
Fish
Have scales. Are steamlined. Have fins for movement/ swimming and balance. Eyes. Lateral line in body detects vibrations in water. Breathe dissolved oxygen from water using gills. Jelly-covered eggs.
Amphibians
Have smooth, moist skin. Limbs. Webbed feet. Fertilisation is external (eggs). Development is external - they return to water to breed. Use lungs on land. Breathe through skin in water.
Reptiles
Have dry, scaly skin. 4 legs except snakes. Internal fertilisation, external development: eggs with rubbery, waterproof shells are laid on land. Have lungs for breathing on land. Cold-blooded.
Birds
Have feathers. Front limbs are modified as wings. Some have webbed feet. No teeth. Beaks. Fertilisation is internal. Development is external - eggs are laid on land, protected by hard shells. Are homeothermic (warm-blooded): regulates body temperature.
Mammals
Have fur. 4 limbs. Fertilisation and development is internal. Female mammals suckle their young on milk from mammary glands. All mammals use lungs for breathing. Are homeothermic.
Describe the main features of flowing plants
Are multi-cellular - each cell is surrounded by a cellulose cell wall and those in leaves and some stems contain chloroplasts which contain the green pigment chlorophyll, whcih absorbs light for photosynthesis.
Have stems, roots and leaves.
Have transport systems consisting of tiny tubes called xylem vessels, which carry water and mineral salts and phloem tubes, whcih transport dissolved food.
State the differences between dicotyledons and monocotyledons
Dicotyledons
Have two cotyledons and broad leaves with a network of branching veins.
Monocotyledons
Have one cotyledon in their seeds and leaves with parallel veins.
State the main features of the three groups of microorganisms: bacteria, fungi and viruses
Bacteria
Consists of single cells. Each bacterial cell has cytoplasm surrounded by a cell membrane and cell wall, but has no nucleus. Has a loop of DNA in plasmids within cytoplasm. No chloroplasts or mitochondria. Some have extensions called flagella for moving through water or other fluids.
Fungi
Each cell has a nucleus and cell wall. The main fungus body is called the mycelium. Fungi are made up of threads called hyphae. These grow over the food supply, digest it externally and the absorb it. Reproduce by making spores that are carried by the wind. Most are sapotrophs - meaning they feed on dead or decaying matter. Some are parasites.
Viruses
Cannot be seen under the light microscope. Smaller than bacteria, they consist of nucleic acid (e.g. DNA) surrounded by a protein coat. They can only reproduce inside livin cells of another organism (the host).
Use simple dichotomous keys to identify plants and animals
Dichotomous keys are used to identify organisms, such as plants and animals
Identify the external features of animals and plants that are useful for making keys
A dichotomous key includes a series of paired statements or questions which lead to an identification.