Biology Definitions

Front 1

What is the meaning of nutrition?

Back 1

Nutrition is the 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.

Front 2

What is the meaning of excretion?

Back 2

Excretion is the removal from organisms of
(1) toxic materials,
(2) the waste products of metabolism (chemical reactions in cells including respiration), and
(3) substances in excess of requirements.

Front 3

What is the meaning of respiration?

Back 3

Respiration is the chemical reaction that breaks
down nutrient molecules in living cells to release
energy.

Front 4

What is the meaning of sensitivity?

Back 4

Sensitivity is the ability to detect or sense changes
in the environment (stimuli) and to make responses.

Front 5

What is the meaning of reproduction?

Back 5

Reproduction is the process that makes more of
the same kind of organism.

Front 6

What is the meaning of growth?

Back 6

Growth is a permanent increase in size and dry
mass by an increase in cell number, cell size or
both.

Front 7

What is the meaning of movement?

Back 7

Movement is an action by an organism or part of
an organism causing a change of position or place.

Front 8

What is the meaning of binomial system?

Back 8

The binomial system is a system in which the scientific name of an organism is made up of two parts showing the genus and species.

Front 9

What is the meaning of tissues?

Back 9

Tissues are a group of cells with similar structures, working together to perform a shared function.

Front 10

What is the meaning of an organ?

Back 10

Organs are structures made up of a group of tissues, working together to perform specific
functions.

Front 11

What is the meaning of organ systems?

Back 11

Organ systems are a group of organs with related functions, working together to perform body functions.

Front 12

What is the meaning of diffusion?

Back 12

Diffusion is the net movement of molecules 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.

Front 13

What is the meaning of active transport?

Back 13

Active transport is the movement of ions in or out of a cell through the cell membrane, from a region of their lower concentration to a region of their higher concentration against a concentration gradient, using energy released during respiration.

Front 14

What is the meaning of osmosis?

Back 14

Osmosis is the diffusion of water molecules from a region of their higher concentration (dilute solution) to a region
of their lower concentration (concentrated solution), through a partially permeable
membrane.

Front 15

What is the meaning of catalyst?

Back 15

Catalyst is a substance that speeds up a chemical reaction and is not changed by the reaction.

Front 16

What is the meaning of enzymes?

Back 16

Enzymes are proteins that function as biological catalysts.

Front 17

What is the meaning of photosynthesis?

Back 17

Photosynthesis is the fundamental process by which plants manufacture carbohydrates from raw materials using energy
from light.

Front 18

What is the meaning of the term limiting factor ?

Back 18

A limiting factor is something present in the environment in such short supply that it restricts life processes.

Front 19

What is the meaning of ingestion?

Back 19

Ingestion is the taking of substances (e.g. food, drink) into the body through the mouth.

Front 20

What is the meaning of egestion?

Back 20

Egestion is the passing out of food that has not been digested, as faeces, through the anus.

Front 21

What is the meaning of digestion?

Back 21

Digestion is the break-down of large, insoluble food molecules into small, watersoluble molecules using mechanical and chemical processes.

Front 22

What is the meaning of absorption?

Back 22

Absorption is the movement of digested food molecules through the wall of the intestine
into the blood or lymph.

Front 23

What is the meaning of assimilation?

Back 23

Assimilation is the movement of digested food molecules into the cells of the body where
they are used, becoming part of the cells.

Front 24

What is the meaning of deamination?

Back 24

Deamination is the removal of the nitrogen containing part of amino acids to form urea, followed by release of energy from the remainder of the amino acid

Front 25

What is the meaning of transpiration?

Back 25

Transpiration is the evaporation of water at
the surfaces of the mesophyll cells followed by loss of water vapour from plant leaves, through the stomata.

Front 26

What is the meaning of translocation?

Back 26

Translocation is the movement of sucrose and amino acids in phloem;
• from regions of production
• to regions of storage OR to regions of utilisation in respiration or growth.

Front 27

What is the meaning of circulatory system?

Back 27

The circulatory system is a system of tubes with a pump and valves to ensure one-way flow of blood.

Front 28

What is the meaning of double circulation?

Back 28

Double circulation is a low pressure circulation to the lungs and a high pressure circulation to the body tissues

Front 29

What is the meaning of aerobic respiration?

Back 29

Aerobic respiration is the release of a relatively large amount of energy in cells by the breakdown of food substances in the presence
of oxygen

Front 30

What is the meaning of anaerobic respiration ?

Back 30

Anaerobic respiration is the release of a relatively small amount of energy by the
breakdown of food substances in the absence of oxygen.

Front 31

What is the meaning of sense organs?

Back 31

Sense organs are groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals.

Front 32

What is the meaning of hormone?

Back 32

A hormone is a chemical substance, produced by a gland, carried by the blood, which alters the activity of one or more specific target
organs and is then destroyed by the liver.

Front 33

What is the meaning of homeostasis?

Back 33

Homeostasis is the maintenance of a constant internal environment.

Front 34

What is the meaning of a drug?

Back 34

A drug is any substance taken into the body that modifies or affects chemical reactions in the body.

Front 35

What is the meaning of asexual reproduction?

Back 35

Asexual reproduction is the process resulting in the production of genetically identical offspring from one parent

Front 36

What is the meaning of sexual reproduction?

Back 36

Sexual reproduction is the process involving the fusion of haploid nuclei to form a
diploid zygote and the production of genetically
dissimilar offspring.

Front 37

What is the meaning of pollination?

Back 37

Pollination is the transfer of pollengrains from the male part of the plant (anther
of stamen) to the female part of the plant (stigma).

Front 38

What is the meaning of growth and development?

Back 38

Growth is a permanent increase in size and dry mass by an increase in cell number or cell size or both.

Development is an increase in complexity .

Front 39

What is the meaning of inheritance?

Back 39

Inheritance is the transmission of genetic information from generation to
generation.

Front 40

What is the meaning of chromosomes?

Back 40

Chromosome is the thread of DNA, made up of a string of genes.

Front 41

What is the meaning of a gene?

Back 41

A gene is the length of DNA that is the unit of heredity and codes for a specific protein. A gene may be copied and passed on to the next generation

Front 42

What is the meaning of an allele?

Back 42

An allele is any of two or more alternative forms of a gene.

Front 43

What is the meaning of a haploid nucleus?

Back 43

A haploid nucleus is a nucleus containing a single set of unpaired chromosomes (e.g.sperm and egg)

Front 44

What is the meaning of a diploid nucleus?

Back 44

A diploid nucleus is a nucleus containing two sets of chromosomes (e.g. in body
cells).

Front 45

What is the meaning of mitosis?

Back 45

Mitosis is nuclear division giving rise to genetically identical cells in which the
chromosome number is maintained by the exact duplication of chromosomes

Front 46

What is the meaning of meiosis?

Back 46

Meiosis is reduction division in which the chromosome number is halved from diploid to haploid.

Front 47

What is the meaning of genotype?

Back 47

Genotype is the genetic makeup of an organism in terms of the alleles present (e.g. Tt or GG)

Front 48

What is the meaning of phenotype?

Back 48

Phenotype is the physical or other features of an organism due to both its genotype and its environment (e.g. tall
plant or green seed).

Front 49

What is the meaning of homozygous?

Back 49

Homozygous is having two identical alleles of a particular gene (e.g. TT or gg). Two
identical homozygous individuals that breed together will be pure-breeding.

Front 50

What is the meaning of heterozygous?

Back 50

Heterozygous is having two different alleles of a particular gene (e.g. Tt or Gg), not pure-breeding

Front 51

What is the meaning of dominant?

Back 51

Dominant is an allele that is expressed if it is present (e.g. T or G)

Front 52

What is the meaning of recessive?

Back 52

Recessive is an allele that is only expressed when there is no dominant allele of the gene present (e.g. t or g).

Front 53

What is the meaning of mutation?

Back 53

Mutation as a change in a gene or chromosome

Front 54

What is the meaning of natural selection?

Back 54

Natural selection is the greater chance of passing on of genes by the best adapted organisms

Front 55

What is the meaning of genetic engineering?

Back 55

Genetic engineering is taking a gene from one species and putting it into another species

Front 56

What is a food chain?

Back 56

A food chain is a chart showing the flow of energy (food) from one organism to the next beginning with a producer (e.g. mahogany tree → caterpillar → song bird → hawk).

Front 57

What is a food web?

Back 57

A food web is a network of interconnected food chains showing the energy flow through part of an ecosystem

Front 58

What is a producer?

Back 58

A producer is an organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis.

Front 59

What is a consumer?

Back 59

A consumer is an organism that gets its energy by feeding on other organisms.

Front 60

What is a herbivore?

Back 60

A herbivore is an animal that gets its energy by eating plants.

Front 61

What is a carnivore?

Back 61

A carnivore is an animal that gets its energy by eating other animals

Front 62

What is a decomposer?

Back 62

A decomposer is an organism that gets its energy from dead or waste organic matter.

Front 63

What is an ecosystem?

Back 63

An ecosystem is a unit containing all of the organisms and their environment, interacting together, in a given area e.g. decomposing log or a lake

Front 64

What is a trophic level?

Back 64

A trophic level is the position of an organism in a food chain, food web or pyramid of biomass, numbers or energy.

Front 65

What is population?

Back 65

Population is a group of organisms of one species, living in the same area at the same time.