bio paper 2 definitions

Homeostasis

Homeostasis

The regulation of conditions of a cell or organism to maintain optimum conditions for function in response to internal and external cell functions

Effectors

Muscles or glands which bring about responses which restore optimum levels

Stimuli

Changes to the environment

Coordination Centres

Areas of the body like the brain spinal cord and pancreas that receive and process info from receptors

Receptors

Organs or cells that detect stimuli

The CNS (central nervous system)

Brain and spinal cord which coordinate the response of effectors

Target organ

The organ which a hormone acts on to produce an effect

Negative feedback cycle

A regulatory mechanism that reverses a change

Thyroxine

A hormone produced by the thyroid gland that increases the basal metabolic rate in the body.

Adrenaline

A hormone that is produced by the adrenal glands in response to fear or stress which increases heart rate and boosts delivery of blood to the brain and muscles as part of the "fight or flight “ response

Reflex

Rapid, automatic responses to certain stimuli that don't involve the conscious of the brain

Reflex are

Passage of info in a reflex (receptor to effector)

Hormones

Chemicals which control things in organs and cells that need constant adjustment

Basal metabolic late

Speed at at which chemical reactions in the body other while the body nest

Neurone

Cell which carries electrical impulses

Sensory neurone

Neurones that carry info as electric impulses from receptor to CNS

Motor neurone

Neurones that carry electrical impulses from the CNS to effectors

Synapse

Gap between 2 neurones

Type 1 diabetes

Pancreas fails to produce sufficient-insulin which causes uncontrollably high blood glucose levels

Type 2 diabetes

Body cells no longer respond to insulin produced by the pancreas

Thermoregulatory centre

An area of the hypothalamus in the brain which contains blood temperature receptors and regulates temperature

Vasoconstriction

The construction of lumen of blood vessels ( in response to low body temp)

Vasodilation

The dilation of blood vessels (in response to high body temp)

Gland

A group of cells that secrete chemicals called hormones into the bloodstream

Glucagon

A hormone produced by the pancreas that causes glycogen to be converted into glucose and released into the blood

Follicle stimulating hormone (FSH)

A female reproductive hormone that causes the maturation of an egg in the ovary

Lutenising hormone

Female reproductive hormone which stimulates the release of an egg

Oestrogen

The main female reproductive hormone which causes the uterus lining to grow and repair

progesterone

A hormone produced in the overuse after ovulation, maintaining the uterus during the 2nd half of the cycle, inhibiting the release of LH and FSH

progesterone

Main male reproductive hormone produced in the testes ord stimulates sperm production

IVF (in vitro fertilisation )

Fertilising en woman's egg using sperm outside of the body

Contraception

Method used to prevent pregnancy

Adult cell cloning

A type of cloning that forms an embryo from an adult body cell

Sexual reproduction

A form of reproduction involving the fusion of male and female gametes. Creates genetic variation

Sex chromosomes

A pair of chromosomes responsible for the determination of the gender. XY in males ,XX in females

Chromosomes

A section of DNA that carries genetic info in the form of genes

DNA ( deoxyribonucleic acid )

A double stranded polymer wound to form a double polymer. Carries the genetic code

Gene

A section of DNA that codes for a specific sequence of amino ands which undergo polymerisation to form a protein .

Genome

The complete material genetic of an organism

Gene

An organism's genetic composition.describes all alleles

Phenotype

An organism’s observable characteristics. Due to interactions of the genotype and the environment

Allele

Different version of the same gene

Dominant allele

An allele that is always expressed. Represented by a capital letter

Recessive allele

Allele that is only expressed is the absence of a dominant allele

Cystic fibrosis

A cell membrane disorder resulting from the presence of a recessive allele

Heterozygous

When someone has 2 different alleles of a gene e.g. Ff

Homozygous.

When someone has two identical alleles of a gene e.g. ff

Polydactyly

A condition where the individual has extra fingers or toes caused by the dominant allele

Mitosis

A form of cell of cell division that produces 2 genetically identical daughter cells (with a full set ofchromosomes) from one parent cell

Meiosis

A form of cell division that produces gametes, non-identical cells with half the usual number of chromosomes

MRSA

A type of bacteria that is resistant to the antibiotic methicillin

Embryo screening

A procedure used to determine the presence of faulty genes in an embryo produced by IVF. A few embryonic cells are remove and screened for defective alleles

Charles Darwin

The scientist who developed the theory of evolution by natural selection.

Evolution

The gradual change in the inherited traits in a population over time - occurs due to natural selection

Natural selection

The process by which the frequency of advantageous traits passed on in genes gradually increases in a population over time.

Species

A group of similar organisms that are able to breed with one another to produce fertile offspring.

Speciation

The formation of new species in the course of evolution, after due to to evolution of 2 isolated populations

Variation

The differences between individuals due to genes, the environment on a combo of both

Evolutionary tree

A diagram which illustrates the evolutionary relationships between organisms

Family tree.

A chart used to show the inheritance of a condition in a family

Classification

The organisation y organisms into groups based on their characteristics and structure

Binomial system

The universal system of naming organisms using their genus and species

Three domain system

A method of classification in which organising and categorised into 3 groups: archaea, bacteria, eukaryota. Developed by Carl Woese.

Archaea

Primitive bacteria living in extreme environments

Linnaean system

The classification of organising into kingdom, phylum, class, order, family, genus , species, developed by Carl Linnaeus

Extinction

The death of all members of a species.

Fertilisation

The fusion of the nucleus of male and female gametes. Restores the full chromosome number.

Genetic engineering

The modification gate of the genome of an organism by the insertion ofa desired gene from another organism enabling the formation of organisms with beneficial characteristics

GM crops

Crops that have had their genomes modified by the insertion of a desired gene from another organism

Inbreeding

The formation of offspring from the breeding of closely related individuals

Selective breeding

Process by which humans artificially select organisms with desirable characteristics and breed them to produce offspring with desirable phenotypes.

Vector

A carrier used to transfer a gene from one organism to another

Protein synthesis

A formation of a protein from a gene

Punnett square

A grid used to predictthe potential outcomes of a genetic cross

Haploid

A cell that contains a single set of chromosomes

Diploid

A cell containing 2 copies of each chromosome

Ecosystem

A community of organisms (biotic) and non-living components (abiotic) of an area and their interactions

Community

All the populations of different species living together in a habitat

Habitat

The place where an organism lives

Population

All organisms of the same species living with one another in a habitat.

Biodiversity

The variety of living organism is an ecosystem

Biotic factors

The living components of an ecosystem e.g. Food availability, pathogens, predators and other species

Abiotic factors

The non living aspects of an ecosystem e.g. Temperature, light intensity, moisture, wind direction, wind intensity, soil pH, soil mineral content, Carbon dioxide levels and oxygen levels

Food chain

Describes the feeding relationships between organising and the resultant stages of biomass transfers, it takes the form: producer → primary consumer → secondary consumer → tertiary consumer.

Predators

Consumers that prey on and eat otheranimals

Prey

Animals that are eaten by predators

Producer

Photosynthetic organisms (e.g. Green plants or algae ) at the start of the food chain that provide biomass for all living things.

Primary consumer

Herb verse that consume producers at trophic level 2 of a food chain

Secondary consumer

Carnivores that consume herbivores at trophies level 3 of a food chain

Tertiary consumer

Carnivores that consume other carnivores at trophies levels 4 and above a food chain

Apex predator

A carnivore at the top of the food chain with no predators

Extremophiles

Organisms that can live in extreme environments e.g. High temperatures, high salinity, high pH

Microorganisms

Very small organisms involved in the recycling of materials in an ecosystem. They return mineral ions to the soil and convert Carbon to carbon dioxide which is released into the atmosphere

Decomposers

Organisms that release enzymes which catalyse the breakdown of dead plant and animal material into simpler organic matter.

Interdependence

The dependence of different organisms on each other for survival e.g. Plants depend on pollinators, herbivores depend on plants

Competition

When different organisms compete for the same resources (e.g. Light, water, mates, territory) in an ecosystem. This limits population sizes and stimulates evolutionary change.

Distribution

The special of living organisms is an ecosystem. it is affected by environmental changes which may be seasonal , geographical or man made

Adaptation

A feature of an organism that increases its chances of survival

Behavioural adaptations

Something an animal does usually in response to some type of external stimulus in order to survive

Structural adaptations

The changes in the structure of a living organism that enables it to adapt better to its environnant