definitions - set 3 Flashcards
egg
a female gamete
embryo
a young organism before birth, and before all the body organs have formed
embryonic stem cell
a cell in an embryo that is capable of giving rise to all types of specialised cell
emphysema
a disease in which the walls of the alveoli in the lungs break down, reducing the surface area for gas exchange
emulsification
breaking large globules of fat into tiny droplets, so that they mix easily with water
endocrine glands
the ductless glands that secrete hormones into the blood and together make up the endocrine system
endothermic
able to internally regulate body temperature; the body temperature is independent of the temperature of the environment
enhanced greenhouse effect
the increase in the greenhouse effect caused by the addition of more greenhouse gases to the atmosphere
enzymes
proteins that function as biological catalysts
epidermis (mammal)
the outer layer of the skin
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
excretion
removal from organisms of the waste products of metabolism (chemical reactions in cells including respiration) toxic materials and substances in excess of requirements
exponential phase
(log phase) the stage in population growth when numbers increase exponentially
evolution
the change in adaptive features of a population over time, as a result of natural selection
F1 generation
the offspring from a parent homozygous for a dominant allele and a parent homozygous for the recessive allele
fermentation
the breakdown of glucose by yeast, using anaerobic respiration; it produces carbon dioxide and alcohol
fertilisation
the fusion of the nuclei of two gametes
fetus
a young organism before birth, once all the body organs have formed
fibrin
an insoluble protein that forms fibres that help in blood clotting
fibrinogen
a soluble protein that is converted to insoluble fibrin when blood clots
filament
the stalk of the stamen
fitness
the probability of an organism surviving and reproducing in the environment in which it is found
flaccid
a term used to describe a cell that has lost a lot of water, becoming soft
follicle
a space inside an ovary in which an egg develops
food chain
a chart showing the flow of energy (food) from one organism to the next beginning with a producer (e.g. mahagony tree - caterpillar - song bird - hawk)
food web
a network of interconnected food chains showing the energy flow through part of an ecosystem
fovea
the part of the retina where cones are most tightly packed
fruit
an ovary of a plant after fertilisation; it contains seeds
FSH
follicle stimulating hormone; a hormone secreted by the pituitary gland which causes the development of eggs in the ovaries
fully permeable
able to let most substances pass through
gametes
sex cells, e.g. eggs and sperm
gas exchange
the entry of oxygen into and organisms body, and the loss of carbon dioxide
gene
a length of DNA that is the unit of heredity and codes for a specific protein
gene mutation
a change in the base sequence of DNA
genetic diagram
the conventional way to set out a genetic cross
genetic engineering
taking a gene from one species and putting it into another species
genotype
the genetic makeup of an organism in terms of the alleles present (e.g. Tt or GG)
genus (plural: genera)
a group of similar and related species
glomerulus
a tangle of blood capillaries in a Bowman’s capsule in the kidney
glucagon
a hormone secreted by the pancreas, which increases blood glucose level
glycogen
the polysaccharide that is used as an energy store in animal cells and fungi
goblet cells
cells which secrete mucus
gravitropism
a response in which a plant grows towards or away from gravity
greenhouse effect
the warming effect of carbon dioxide, methane and other greenhouse gases, on the Earth
growth
a permanent increase in size and dry mass by an increase in cell number or cell size or both
guard cell
one of the two sausage-shaped cells in the epidermis in plants, between which there is a hole called stoma; the guard cells can change shape to open and close the stoma
habitat
the place where an organism lives
haploid
having one set of chromosomes
hepatic portal vein
a blood vessel that transports blood from the digestive system to the liver
hervibore
an animal that gets its energy by eating plants
