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Biology > 4th Form Definitions and Key Concepts > Flashcards

4th Form Definitions and Key Concepts Flashcards

1
Q

diffusion

A

the net movement of substances from an area of high to low concentration, down a concentration gradient and can be across a partially permeable membrane

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2
Q

osmosis

A

the net movement of water from an area of high to low water potential, down a water potential gradient and can be across a partially permeable membrane

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3
Q

active transport

A

the movement of substances from an area of low to high concentration, against a concentration gradient, using the energy from ATP

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4
Q

phloem

A

a tissue in plants that is specialised to transport sugars and amino acids both up and down the plant from the leaves to respiring tissues. this is called translocation

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5
Q

translocation

A

the movement of sugars and amino acids through the phloem

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6
Q

transpiration

A

water loss via evaporation through the stomata in the leaves down a water potential gradient

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7
Q

transpiration stream

A

the upwards movement of water through the xylem from roots to leaves

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8
Q

xylem

A

a tissue that is specialised to transport water from the roots to the leaves. Is dead and hollow to allow the continuous column of water

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9
Q

antidiurectic hormone (ADH)

A

a hormone produced by the pituitary gland that increases the reabsorption of water in the collecting duct of the kidney

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10
Q

bladder

A

the organ that collects and holds urine before it is excreted

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11
Q

Bowman’s capsule

A

structure at the start of the nephron where the glomerular filtrate enters from the glomerulus and connects to the proximal convoluted tubule

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12
Q

collecting duct

A

final part of the nephron which connects to the ureter where water is reabsorbed, how much is determined by its permeability which is controlled by ADH

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13
Q

convoluted tubules

A

tubes in the nephron (PCT and DCT) where the filtrate flows through, substances (glucose, ions, amino acids) from the filtrate are reabsorbed by active transport into the blood from these tubes

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14
Q

excretion

A

the removal of metabolic waste from the body (co2 for example)

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15
Q

glomerulus

A

a bundle of capillaries where ultrafiltration occurs

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16
Q

loop of henle

A

part of the nephron after the PCT where water and salts are reabsorbed

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17
Q

nephron

A

functional unit of the kidney that contains the bowman’s capsule, PCT, Loop of Henle, DCT and collecting duct

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18
Q

organs of excretion

A

any organ that removes metabolic waste, the lungs removing carbon dioxide and water vapour produced from respiration, the kidneys removing water, urea and salts and the skin excreting water and salts

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19
Q

osmoregulation

A

regulation of the volume of water in body fluids by the use of the hormone ADH

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20
Q

selective reabsorption

A

the selective uptake of useful substances such as glucose, water and ions back into the blood from the nephron. selective reabsorption in the PCT involves the active transport of glucose out of the PCT back into the blood

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21
Q

stomata

A

small holes found in the lower epidermis that open and close thanks to the guard cells. control the loss of water by closing during the night but open during the day thanks to the guard cells to allow the diffusion of carbon dioxide and oxygen

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22
Q

ultrafiltration

A

the filtration of blood at the glomerulus under high pressure to form the glomerular filtrate. contains water, ions, glucose, urea and other molecules. does not contain proteins and blood cells as they are too large and cannot leave due to the basement membrane

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23
Q

ureter

A

tubes that carry urine from the kidneys to the bladder

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24
Q

urethra

A

tube that carries urine from the bladder out of the body

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25
Q

urine

A

waste product of the kidney that contains water, urea and ions

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26
Q

follicle stimulating hormone (FSH)

A

a hormone produced by the pituitary gland that stimulates the growth of follicles in the ovary and stimulates the release of oestrogen

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27
Q

luteinising hormone (LH)

A

a hormone secreted by the pituitary gland that stimulates ovulation (the release of an egg from the ovary) and the release of progesterone

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28
Q

progesterone

A

a hormone produced in the ovaries, specifically by the corpus luteum and the placenta that maintains the uterus lining and inhibits the release of FSH and LH

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29
Q

amniotic fluid

A

the fluid that surrounds and protects the embryo from bumps and sudden changes from the mother in the uterus

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30
Q

asexual reproduction

A

a form of reproduction involving a single parent CELL. it created genetically identical offspring which have survival value in a stable environment. usually producing large numbers of offspring and quickly

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31
Q

cuttings

A

method of cloning plants. a section of the stem is cut, with at least one leaf, from a parent plant that you want to clone and is replanted in damp compost with hormones that stimulate root growth (auxins)

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32
Q

embryo

A

an unborn organism in an early stage of development formed by mitosis

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33
Q

fertilisation

A

the fusion of the nucleus of a male and female gametes to form a diploid zygote

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34
Q

gametes

A

sex cells, sperm in males and egg cells in females, each being haploid (half the number of chromosomes). Pollen is the male gamete of a plant

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35
Q

germination

A

seeds need oxygen (for respiration), warmth (for enzymes), water (activate enzymes) to germinate. this occurs until photosynthesis can take place in the leaves, then germination has finished.

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36
Q

menstrual cycle

A

a monthly cycle in women that involves the growth of the uterus lining, release of an egg, maintenance of the uterus lining and then its shedding

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37
Q

meiosis

A

a form of cellular division that produces gametes, genetically different, haploid cells. 4 daughter cells produced over two divisions involving two parent CELLS only occurs in the reproductive organs and used to produced gametes

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38
Q

mitosis

A

a form of cellular division that produces two genetically identical, diploid cells from a single parent CELL. 2 daughter cells produced over one division, occurs everywhere in the body and used for the growth and repair of cells/tissues

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39
Q

monohybrid cross

A

a cross between two organisms that is used to investigate the inheritance of a single gene

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40
Q

oestogen

A

female reproductive hormone that causes the uterus lining to develop. It inhibits FSH. also responsible for the development of the secondary sexual characteristics

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41
Q

placenta

A

attached to the uterus lining during pregnancy. acts as an exchange surface between the mother and foetal blood where glucose (for respiration), amino acids (for protein synthesis) and oxygen (for respiration) diffuse into the foetal blood and waste products like carbon dioxide and urea diffuse into the mother’s blood. also produces progesterone

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42
Q

pollination

A

transfer of pollen grains (either by wind or insects) from the anther to the stigma, where fertilisation occurs. can be self-pollination (same flower) or cross pollination (flowers on different plants). also wind or insect pollination

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43
Q

wind pollinating flowers

A

exposed stigma and stamen, dull/colourless flowers, no nectar, small and smooth pollen grains, feathery stigma

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44
Q

insect pollinating flowers

A

enclosed stigma and stamen, large, colourful petals with nectar present, stigma is sticky and large, sticky pollen grains

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45
Q

secondary sexual characteristics

A

features that appear during puberty and differ between genders. examples; voice changing, growth of hair, development of breasts, hips widening, growth of male reproductive organs, start of menstrual cycle

46
Q

sexual reproduction

A

a form of reproduction that involves the fusion of male and female gametes, creating genetic variation in the offspring and has survival value in a changing environment. involves two parent CELLS

47
Q

testosterone

A

the main male reproductive hormone, produced by the testes, stimulates sperm production (along with FSH) and responsible for the development of male secondary sexual characteristics

48
Q

zygote

A

a fertilised egg cell (diploid)

49
Q

allele

A

an alternative version of a gene that cause difference in inherited characteristics such as hair colour

50
Q

chromosome

A

a long, coiled molecule of DNA that carries genetic information in the form of genes

51
Q

codominance

A

two different alleles both being expressed in the phenotype

52
Q

deoxyribonucleic acid (DNA)

A

double stranded polymer arranged in a double helix, made up of DNA nucleotides that carry the genetic code. there are 4 DNA nucleotides, each made up of a phosphate molecule and a deoxyribose sugar but differ due to their nitrogenous base, adenine, thymine, cytosine and guanine

53
Q

dominant

A

the allele that is always expressed in the phenotype when in the genotype, denoted by a capital letter

54
Q

evolution

A

the change in inherited traits within a population over time. modelled by natural selection

55
Q

gene

A

a section of DNA that codes for a specific sequence of amino acids that forms a protein and is responsible for a particular trait (phenotype)

56
Q

genome

A

the complete genetic material of an organism

57
Q

genotype

A

all of the alleles present in an organism

58
Q

haploid

A

a cell that contains half the amount of genetic information. Human gametes have 23 chromosomes (it only contains 1 chromosome of each homologous pair)

59
Q

heterozygous

A

when an organism has two different alleles of a gene, e.g. Gg

60
Q

homozygous

A

when an organism has two of the same alleles, e.g. GG/gg

61
Q

mutagens

A

chemicals that increase the frequency of mutations in DNA

62
Q

mutation

A

a random change in DNA which may result in genetic variations that can produce a slightly different protein and therefore a different phenotype if the mutation occurs in a gene. examples being addition, substitution and deletion

63
Q

natural selection

A

a change in the environment (selection pressure) causes an organism with a mutated allele to be at an advantage, they are more likely to survive, reproduce and pass on their advantageous, mutated allele to their offspring. this happens over many generations and results in the mutated allele becoming more frequent in the population at the expense of the previously dominant allele

64
Q

nucleus

A

an organelle found in most eukaryotic cells that contain the genetic material of the cell and controls the activities of the cell

65
Q

phenotype

A

an organisms visual characteristics due to the organism’s genotype and interactions with the environment. e.g. hair colour

66
Q

recessive

A

an allele that is only expressed in the phenotype when present with another recessive allele in the genotype (homozygous). Denoted by a lower case letter, e.g. q

67
Q

sex chromosomes

A

a pair of chromosomes that determine the sex of an individual. In humans this is the 23rd pair and is XX in females and XY in males

68
Q

variation

A

the differences between individuals due to genes, the environment or a combination of both

69
Q

abiotic factors

A

non-living parts of an ecosystem, e.g. temperature, light intensity, moisture, wind speed, soil pH, mineral concentration, carbon dioxide and oxygen levels

70
Q

biodiversity

A

variety of living organisms in an ecosystem. It takes into account the number of different species and the population of each

71
Q

biotic factors

A

living components of an ecosystem, e.g. food availability, pathogens, predation and competition (interspecific competition – competition between members of different species and intraspecific competition – competition between members of the same species)

72
Q

community

A

all the populations of different species living together in a particular place at a particular time

73
Q

distribution

A

spread of living organisms in an ecosystem, affected by environment changes

74
Q

ecosystem

A

the community of organisms (biotic) and non-living components (abiotic) of a particular area and how they interact with one another

75
Q

habitat

A

the place in an ecosystem when an organism lives

76
Q

population

A

all the organisms of the same species living with one another in a habitat at any one time

77
Q

decomposers

A

organisms that release enzymes which speed up the breakdown of dead plant and animal material, e.g. bacteria and fungi

78
Q

decomposition

A

the breakdown of dead materials into simpler organic matter that can eventually be absorbed by plants. the rate at which it occurs is affected by temperature, water and oxygen content

79
Q

energy transfers

A

the flow of energy from one trophic level to the next. Is never 100% and decreases the further you move up the food chain due to not all of the organism being eaten, not all of it being digested, some of the energy being used in respiration/movement of the organism and some energy being lost in the excretory products

80
Q

food chain

A

shows the feeding relationships between organisms and the stages of biomass transfer. the arrows represent the flow of energy between organisms

81
Q

food web

A

network of food chains that shows how energy can flow in different ways and that animals can feed on more than one organism

82
Q

primary consumer

A

herbivores that consume producers in a food chain

83
Q

producers

A

photosynthetic organisms at the start of the food chain that provide biomass for all the organisms in the food chain

84
Q

pyramid of biomass

A

a pyramid, with each layer of the pyramid representing the amount of mass of living material at each trophic level of a food chain. When asked to draw one in exams, they often start off bigger at the bottom and get smaller at each level above

85
Q

pyramid of number

A

a pyramid showing the numbers of each organisms at each trophic level, often looking similar to the pyramid above but if the producer is large and small in number, like a tree, can look quite different

86
Q

quadrat

A

a square grid used to sample populations and to determine abundance and distribution of organisms in an ecosystem

87
Q

quaternary consumers

A

carnivores that consume tertiary consumers

88
Q

secondary consumers

A

carnivores that consume primary consumers

89
Q

teritary consumers

A

carnivores that consume secondary consumers

90
Q

top carnivore/apex predator

A

an organism in a food chain/web that is not consumed by another

91
Q

trophic level

A

the position of an organism in a food chain. only around 10% of the energy is transferred from one level to the next

92
Q

carbon cycle

A

the cycle where carbon moves between organisms and the environment, namely in the form of carbon dioxide and involving respiration, photosynthesis, fossilisation and combustion

93
Q

decomposers in the nitrogen cycle

A

organisms that release enzymes that catalyse the breakdown of dead plant and animal material releasing nitrogen containing compounds such as ammonia into the soil

94
Q

denitrifying bacteria

A

bacteria that convert nitrates in the soil into nitrogen gas. occurs when conditions are anaerobic and can be prevented by ploughing the soil to aerate the soil and having good drainage to prevent the air spaces from filling with water, both ensuring there is adequate amounts of oxygen to prevent the growth of these organisms

95
Q

nitrifying bacteria

A

aerobic organisms that convert ammonia to nitrites and then nitrates which can be absorbed by plants using active transport in the roots

96
Q

nitrogen cycle

A

the cycle through which nitrogen moves between living organisms and the environment

97
Q

nitrogen fixing bacteria

A

bacteria that convert nitrogen gas into nitrogen containing compounds that plants can use. can be free living in the soil or found in root nodules of leguminous plants (clover, peas) where they have a mutualistic relationship and convert nitrogen gas to nitrogen containing compounds which the plant receives and in return get sugars from the plant that have been produced via photosynthesis

98
Q

deforestation

A

removal of trees to use the resources on the tree for fuel or for space that the trees occupy

99
Q

eutrophication

A

pollution of water by fertilisers being added in nearby land and nutrients leaching into the water causing excessive growth of algae at the surface of the water (algal bloom), which prevents light reaching photosynthetic plants at the bottom of the water, causing them to die, reducing the oxygen levels in the water and eventually resulting in the death of all aerobic organisms in the water

100
Q

global warming

A

rise in average temperatures on earth due to increased levels of greenhouse gases like carbon dioxide, causing the enhanced greenhouse effect where more heat is trapped in the atmosphere and once reflected off the surface is reflected back to the surface rather than escaping

101
Q

greenhouse gases

A

gases in the earth’s atmosphere that trap heat and cause the greenhouse effect, examples being water vapour, carbon dioxide, methane, nitrous oxide and CFCs

102
Q

leaching

A

movement of nutrients e.g nitrates in the soil into lakes and rivers due to rain and can lead to eutrophication

103
Q

pollution

A

contamination or destruction of the environment due to human impacts

104
Q

biological control of pests

A

use of other species to kill pests, e.g. hawks to control the rat population

105
Q

interspecific predation

A

where an organism of one species kills an organism of a different species, e.g. in fish farming one species of fish killing another species of fish for food in the same tank. this can be reduced by separating fish of different species into separate tanks

106
Q

intraspecific predation

A

where an organism of one species kills an organism of the same species. In fish farming this can be reduced by separating fish by age and size in different tanks

107
Q

lactobacillus

A

a bacterial species used to make yoghurt

108
Q

pesticides

A

chemicals used to kill pests. can be split into herbicides which are used to kill weeds and insecticides which are used to kill insects

109
Q

yeast

A

unicellular fungi used to produce bread. they anaerobically respire to produce carbon dioxide which makes the bread rise and the ethanol which is also produced evaporates when the bread is heated

110
Q

selective breeding

A

process where organisms with desirable characteristics are selected to breed and produce offspring with the desirable characteristics. can be used for both plants and animals

Biology (84 decks)

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