Key Terms Flashcards
Active transport
The movement of substances against a concentration gradient and/or across a cell membrane using energy
ADH
The hormone which controls the selective reabsorption of water in the kidneys
Aerobic respiration
The process by which food molecules are broken down using oxygen to release energy for cells
Allele
A version of a particular gene
Anaerobic respiration
Cellular respiration in the absence of oxygen
Asexual reproduction
Reproduction which involves only one parents a produces offspring which are genetically identical to their parents
Auxins
Plant hormones which are involved in controlling the phototropisms
Carbohydrates
Food group which includes the sugars and starches. They are important for providing energy for the cells
Cell
The basic unit of all living organisms
Cellular respiration
Respiration which takes place in the cytoplasm and mitochondria of the cells
Cellulose cell walls
The rigid cell wall which surrounds plant cells
Chlorophyll
The green pigment contained in the chloroplast which captures light energy from the sun
Chloroplasts
The plant organelles which contain chlorophyll. They are the site of photosynthesis
Clone
Offspring produced by asexual reproduction that are identical to their parent organism
Codominance
Two alleles which are both expressed in the phenotype of an organism
Consumers
Organisms which feed on other organisms, eg. primary consumers eat plants
Cytoplasm
The water-based gel in which the organelles of all living cells are suspended
Decomposers
Microorganisms that break down waste products and dead bodies
Denatures
The breakdown of the structure of a protein molecule if the temperature gets too hot, or if the pH changes
Diastole
The stage of the cardiac cycle when the heart fills with blood
Differentiate
The process by which unspecialised cells become specialised for a particular function
Diffusion
The net movement of particles of a gay or a solute from an area of high concentration to an area of low concentration down a concentration gradient
Diploid
Having two sets of chromosomes in the nucleus of the cells: one from the male parent and one from the female parent
Disperse
The spreading of seeds away from the parent plant
Dominant
A characteristic which will show up in the offspring even if only one of the alleles is inherited
Double circulation
The separate circulation of the blood from the heart to the lungs and then back to the heart again and from the heart to the body and back to the heart
Ecosystem
All of the animals and plants living in an area, along with the things that affect them, such as the soil and the weather. An ecosystem includes all the interactions between the many different types of living organisms and the non-living components of their home
Egestion
The removal of undigested food from a cell or from the body in the form of faeces
Endocrine Glands
The glands which produce hormones and secrete them directly onto the blood
Enzyme
A protein molecule which acts as a biological catalyst, speeding up the rate of reaction without being used up or affected. They are sensitive to both temperature and pH
Eutrophication
When a lake of river becomes enriched with nutrients, eg. from fertiliser applied to fields, excess plant growth is followed by decay. Microorganisms use up oxygen from the water so that other organisms can no longer survive
Fermentation
Another term for anaerobic respiration which is particularly used for microorganisms such as yeast. Glucose is partly broken down into ethanol or lactic acid with the release of a small amount of energy
Fertilisation
The joining of the haploid male and female gametes to form a new diploid individual
Gametes
The haploid sex cells which contain only one set of chromosomes. Male gametes include sperm and pollen, female gametes include ova and ovules
Genetically Modified organism
Organisms which have had DNA from a different species or a different individual inserted in their genome
Genotype
The genetic make up of an organism concerning the alleles of a particular gene
Global Warming
An increase in the temperature at the surface of the Earth due to greenhouse gases in the atmosphere trapping infrared radiation from the surface
Glycogen
The carbohydrate energy store found in the liver and muscles of animals. It can be converted back into glucose when energy is needed in cells
Greenhouse gases
Gases such as carbon dioxide and methane in the atmosphere which absorb infrared radiation from the surface of the Earth and radiate it back to the surface, contributing to the greenhouse effect
Habitat
The place where an animal or plant lives, including both the living and non-living aspects of the area
Haploid
Having only one set of chromosomes in the nucleus of the cell
Heterozygous
When the two alleles for a particular gene on a pair of chromosomes are different, eg. Tt
Homozygous
When the two alleles for a particular gene on a pair of chromosomes are the same, eg. TT or tt
Hormones
Chemical messages which are secreted by endocrine glands and are carried around the body in the blood to the organs they affect
Hypothalamus
The part of the brain which regulates many body functions, eg. temperature, thirst, hunger and sleeping. It also controls the production of many hormones from the pituitary gland
Invertebrates
Animals which do not have a backbone
Meiosis
A two-stage process of cell division which reduces the number of chromosomes from the diploid parent cell to the haploid daughter cell
Mitochondria
A cell organelle which is the site of aerobic respiration, so they produce most of the energy needed by the cell
Mitosis
Asexual cell division, a single-stage process which results in identical daughter cells
Natural selection
The process by which evolution happens; organisms produce more offspring than the environment can support, and only those best adapted to their environment will survive to breed and pass on their characteristics
Neurone
The basic unit of the nervous system; cells which carry minute electrical impulses around the body
Nitrogen cycle
The continuous natural process by which nitrogen is exchanged between living organisms and the environment
Nucleus
The organelle in the cell which contains the genetic material
Organ
A group of different tissues working together to carry out a particular function in the body
Organ system
A group of organs working together to carry out a particular function in the body
Organelles
Membrane-bound structures found in the cytoplasm of a cell which carry out particular functions in the cell
Osmoregulation
The control and regulation of the levels of mineral ions and water in the cytoplasm of a cell or in the blood of an organism
Osmosis
The net movement of water down a concentration gradient from an area of high water potential to low water potential across a partially permeable membrane
Phenotype
The physical characteristics of an organism with respect to one or more particular genes
Photosynthesis
The process by which plants make food by combining carbon dioxide and water to make glucose using light energy captured using chlorophyll
Phototropisms
The response of a plant through growth to light shining from one side only
Plasmids
The extra circles of DNA containing extra genes found in bacteria and used by scientists in genetic engineering
Population
A group of individuals of the same species living together in the same habitat and breeding together
Positive tropism
A tropism in which the plant moves towards the stimulus
Quadrat
A piece of equipment used to sample an area to investigate the size of a population of plants or slow moving animals. Quadrats are usually square frames of wood or metal that are laid on the ground to outline a sample area
Recessive
A characteristic which shows up in the offspring only when both of the alleles are inherited
Recombinant DNA
DNA which has had a section of DNA from another species or organism inserted into it
Sex chromosomes
The chromosomes which determine the sex of the offspring. In humans, XX is a female and XY is a male
Sexual Reproduction
Reproduction which involves the joining of two special haploid sex cells or gametes to produce diploid offspring which are genetically different from their parents
Synapse
The gap between two neurones where the transmission of the impulse is chemical rather than electrical. Transmission across the synapse depends on neurotransmitters
Systole
The stage of the cardiac cycle when the heart contracts and forces the blood out around the body and to the lungs
Transgenic
An organism which contains DNA from another organism
Transpiration
The loss of water vapour from the surface of the leaves of plants. This occurs through stomata when they are opened to allow the gaseous exchange needed for photosynthesis to take place
Turgor
The state of a plant cell when water has moved in by osmosis so that the cytoplasm is pressing hard against the cellulose cell wall and no more water can enter the cell
Umbilical cord
The structure that connects a fetus to the placenta. Food and oxygen travel from the mother to the developing fetus through the umbilical cord, and waste products such as carbon dioxide and urea pass in the other direction
Vaccination
Giving a dose of a weakened or dead pathogen to stimulate the immune system to produce antibodies and develop immunity to a disease
Xylem
The transport tissue in plants which carries water and mineral ions up from the root through the stems to the leaves
Zygote
The new diploid individual formed when the haploid male and female gametes meet and fuse in sexual reproduction
