Paper 2: Quizlet Import Flashcards
1
Q
define homeostasis
A
regulation of internal conditions of cell or organism to maintain optimum conditions for function in response to internal and external changes
2
Q
examples of homeostasis in body
A
-blood glucose concentration -body temperature -water levels
3
Q
what components do all control systems include
A
-receptors -coordination centres -effectors
4
Q
what are receptors
A
cells that detect stimuli
5
Q
define stimuli
A
changes in environment
6
Q
what are coordination centres and examples
A
-brain, spinal cord, pancreas -receive and process info from receptors
7
Q
what are effectors and examples
A
-muscles or glands -bring about responses to restore optimum levels
8
Q
what is negative feedback
A
body produces response which counteracts a change to restore optimum levels
9
Q
what is the function of the nervous system
A
-enables humans to react to surroundings and coordinate behaviour
10
Q
what is the CNS and function
A
-brain and spinal cord -coordiante response of effectors
11
Q
what are sensory neurones
A
cells that carry info as electrical impulses from receptors to CNS
12
Q
what are motor neurones
A
cells that carry electrical impulses from CNS to effectors
13
Q
what are relay neurones
A
link sensory and motor neurones, carry nerve impulses within CNS
14
Q
how do muscles carry out a response
A
contract
15
Q
how do glands carry out a response
A
secrete hormones
16
Q
how is the CNS connected to the body
A
by motor and sensory neurones
17
Q
nervous system pathway
A
stimulus –> receptor –> sensory neurone –> relay neurone (in CNS) –> motor neurone–> effector –> response
18
Q
what is a reflex
A
rapid, automatic response to stimuli not involving conscious part of brain
19
Q
how are sensory neurones adapted to their function
A
-long axon (move impulse from one part of body to other) -many dendrites to make contact with other nerves -cell body in middle
20
Q
what is a synapse and what happens
A
-gap between neurones -electrical impulse transferred by chemicals that diffuse across gap -trugger new electrical signal in next neurone
21
Q
how is the relay neurone adapted to its function
A
-long axon -many short dendrites
22
Q
how is the motor neurone adapted to its function
A
-many short dendrites -long axon -myelin sheath
23
Q
explain reflex arc x4
A
-receptors detect stimuli (change in environment) -information from receptors pass along neurones as electrical impulses to coordination centre (CNS) -CNS is brain and spinal cord -CNS coordinations a response of effectors, may be muscles contracting or glands secreting hormones
24
Q
required practical for reaction time
A
-person sit with arm resting on edge of table -other person hold ruler vertically between the others thumb and forefinger, zero end is level with thumb -let go with no warning -person tested must catch ruler as soon as possible, reaction time measured by number on top of thumb on ruler -the higher the number, the slower the reaction time -repeat several times and calculate mean distance in cm -repeat after caffeinated drink taken -keep person, height of ruler dropped from same
25
more accurate way of measuring reaction time and why
-computer tests -click mouse as soon as stimulus seen -more precise reaction time (less human error) -more accurate measurement due to higher resolution (milliseconds) -remove possibility of prediction due to body language
26
what is the brain made up of
billions of interconnected neurones and different regions
27
3 regions in brain
-cerebellum -medulla -cerebral cortex
28
function of cerebellum
responsible for msucle coordination
29
function of medulla
control unconscious activities such as breathing and heartbeat
30
function of cerebral cortex
responsible for consciousness, intelligence, memory, language
31
function of brain
-controls complex behaviours
32
methods used to study the brain
-studying patients with brain damage -electrically stimulating brain -MRI scans
33
how does studying patients with brain damage help neuroscientists
-if area in brain damaged by stroke causes patient to go blind for example, then this area is responsible for vision -effect of damage relates to function
34
how does electrically stimulating the brain help scientists
-insert electrode into tissue -give small zap of electricity -observe in effect eg if causes muscle contraction and movement
35
how do MRI scans help scientists
-machine showing detailed picture of brain -can observe which parts of brain active when carrying out a certain action
36
benefits of studying brain
lead to development of treatments for disorders of nervous system
37
why is investigating and treating brain disorders difficult
-brain is complec and delicate, can cause physical damage to brain and further problems such as impaired speech
38
function of eye
sense organ containing receptors sensitive to light intensity and colour
39
what is accomodation
-changing shape of lens to focus on near or distant objects
40
what is adapation
adjusting of eye to dim or bright light
41
components of eye x9
-sclera -cornea -retina -pupil -iris -ciliary muscles -suspensory ligaments -lens -optic nerve
42
function of sclera
-tough, supporting wall of eye -protection
43
function of cornea
-transparent, outer layer -in front of eye -refracts light into eye
44
function of iris
-contain muscles -control diameter of pupil -therefore controls how much light enters eye
45
what is the pupil
-hole in the middle of eye -where light enters through
46
function of lens
-focus light onto retina
47
function of retina
-contains receptor cells -cones sensitive to colour -rods sensitive to light intensity
48
function of ciliary muscles and suspensory ligaments
-control shape of lens
49
function of optic nerve
-carry impulses from receptors on retina to brain
50
how does the eye adjust to bright light
-circular muscles contract -radial muscles relax -pupil smaller= reduce light entering eye
51
how does the eye adjust to dim light
-circular muscles relax -radial muscles contract -pupil is wider=more light enters eye
52
eye changes to look at near objects
-ciliary muscles contract -suspensory ligaments slacken -lens=fatter (more curve) -light refracts more strongly
53
eye changes to look at distant objects
-ciliary muscles relax -suspensory ligaments tighten -lens is thin (less curve) -light refracts less strongly
54
why are some people long sighted or short sighted
-lens cannot refract light by right amount -light not focussed on retina
55
what is hyperopia
-long sightedness -cannot focus on near objects
56
causes of hyperopia
-lens is too thin (not refract light enough) -eyeball too short
57
result of hyperopia
-image formed behind retina
58
correction for hyperopia
-convex lens -refract light more strongly to focus on retina
59
what is myopia
-short sightedness -cannot focus on distant objects
60
causes of myopia
-lens too thick and refract light too much -eyeball too long
61
effect of myopia
-image of far objects brought to focus in front of retina
62
correction of myopia
-concave lens -refract lgiht rays less strongly to focus on retina
63
different treatments for vision defects
-contact lenses -laser eye surgery -replacement lens surgery
64
positives of contact lenses
-more convenient for sports than glasses -lightweight -invisible
65
negatives of contact lenses
-prescription can be expensive -soft lenses can cause risk of eye infection
66
how does laser eye surgery correct vision and benefits
-use laser to change shape of cornea -more precise and can completely correct vision -permanent solution, less maintenance
67
negatives of laser eye surgery
-has complications -cause dry eye -cause infections, worsen vision
68
what happens in replacement lens surgery and positive
-natural lens removed, replacement plastic lens inserted -may be more effective in treating long sightedness than laser eye surgery
69
negatives of replacement eye surgery
-cause possible retina damage -could lead to loss of sight
70
control centre for regulating temperature
-thermoregulatory centre in brain
71
what does the thermoreulatory centre contain
receptors sensitive to temp of blood flowing through brain
72
what does the skin contain to monitor body temp
temperature receptors, send nerbous impulses to thermoreulatory centre
73
response of body when too hot
-blood vessels dilate (vasodilation) -blood flows closer to surface of skin + sweat produced from sweat glands (evaporate from surface of skin) = more energy transferred from skin to environment (heat radiated out)
74
body response when too cold
-hairs erect=trap insulating lsyer of air -no sweat -vasoconstriction= blood vessels constrict, close off skin blood supply -shivering= skeletal muscles contract, requires respiration, releases energy (some transferred to warm body)
75
what is the endocrine system
-composed of glands which secrete chemicals (hormones) directly into bloodstream -blood carries hormones to target organ producing effect
76
defien hormone
chemical messenger released by glands and carried in blood to target organs
77
nervous system vs endorcrine system
NERVOUS: -short term effects -very fast reponse -act on precise area -involves electrical impulses via neurones ENDOCRINE: -long term effects -slower response -involves chemical messengers (hormones) via blood
78
control system of endocrine system and body temperature
hypothamlamus
79
what is the master gland and its function
-pituitary gland in brain -secretes sevral hormones in blood -act on other glands to stimulate other hormones to be released to bring effects
80
thyroid location and function
-in neck -produces thyroxine
81
purpose of thyroxine
-regulates heart rate -regulates temperature -regulates rate of metabolism
82
location and function of adrenal glands
-on top of both kidneys -produce adrenaline
83
purpose of adrenaline
-prepare body for 'fight or flight' response
84
function of ovaries
-produce oestrogen, involved in menstrual cycle
85
function of testes
-produce testosterone -control puberty and sperm production
86
function of pancreas
-produce insulin and glucagon -regulate blood glucose level
87
define metabolism
-sum of all chemical reactions in cells of organism
88
what is blood gluvose concentration regulated by in the body
pancreas
89
what is a negative feedback cycle
-levels of a certain factor kept steady -responds when conditions change from ideal point, aims to return conditions back to this set point
90
what happens when blood glucose levels are too high
-pancreas produces hormone insulin -causes glucose to move from blood into liver and muscle cells -liver and msucle cells convert excess glucose into insoluble glycogen which is stored (in liver and muscles) -therefore, blood glucose level decreases
91
what happens when blood gluvose levels are too low
-pancrease secretes hormone glucagon into blood -causes liver to convert glycgoen into glucose -glucose released into blood by liver -blood glucose level increases
92
what is type 1 diabetes and treatment
-pancreas fails to produce sufficient insulin -blood glucose level can rise to a level that can kill them -treated with insulin injections mainly at mealtimes -makes sure glucose is removed from blood quickly once food difested
93
other treatment for type 1 diabetes
-limiting intake of food rich in simple carbohydrates
94
what is type 2 diabetes and a risk factor
-body cells no longer respond to insulin produced by pancreas -obesity is a risk factor
95
treatment for type 2 diabetes
-carbohydrate controlled diet -regular exercise
96
what does eating foods containing carbs do
-puts glucose into blood
97
where is glycogen stored
-liver and muscles
98
what does vigorous exercise do in relationship to glucose
removes more glucose from blood
99
what happens when when cells are surrounded by fluids with a low concentration
-water enters cells -swell and eventually burst
100
what happens when cells are surrounded by fluids that are very concentrated
-shrivel
101
what happens when body cells lose/gain too much water by osmosis
-do not function efficiently
102
how is water, ions and urea lost in the body
-water lost via lungs during exhalation -water, ions, urea lost from skin in sweat -NO CONTROL OVER THESE
103
role of kidneys
-make urine -take waste producst out of blood (filtered out of blood as it passes through kidneys) =filtration
104
what is selective reabsorption
-useful substances such as glucose, some ions and water absorbed back into blood
105
how is water obtained
via food and drink
106
how are ions obtained
via food and drink
107
how is urea produced and where
-in LIVER excess proteins broken down into amino acids -converted to fats and carbohydrates, stored =DEAMINATION -ammonia produced as waste product (TOXIC) -converted to urea in liver -urea transported to kidneys, filtered out of blood and excreted in urine
108
what upsets the osmotic balance of the body
-too much water -too many ions
109
what is water, ion and urea concentration regulated by
kidneys
110
example of ion taken in body
sodium
111
how is blood filtered
-glucose, water, ions filtered out of blood through semi permeable membrane of kidney tubules (red blood cells etc not small enough to pass through) -glucose diffuses back out into blood until equilibrium reached -rest of glucose is actively transported back into blood (selective reabsorption)
112
water content off blood too high
-receptor in brain detect too high water content -coordiantion centre in brain receives info and cooridnates response -pituitary gland in brain instructed to release less ADH -less water reabsorbed from kidney tubules
113
water content of blood too low
-receptor in brain detect water content too low -coordination centre in brain receive info and coordinates response -pituitary gland release more ADH -more water reabsorbed from kidney tubules
114
what does ADH affect
permeability of kidney tubules
115
where is ADH released from
-pituitary gland
116
what does ADH stand for
anti-diuretic hormone
117
what are examples of diuretics
-coffee -alcohol
118
what is the reabsorption of water controlled by
negative feedback loop
119
what are the effects of kidney failure
-waste substances build up in blood -lose ability to control level of ions and water in body
120
treatments for kidney failure
-kidney dialysis -kidney transplant
121
what happens in kidney dialysis
-person's blood flows between partially permable membranes surrounded by dialysis fluid (membrane only allows ions and waste substances to flow through, not proteins) -dialysis fluid has same concentration of dssiolved ions and glucose as healthy blood -only waste substances such as urea, excess ions and water diffuse across into fluid -waste products removed from the blood, and returned back to body
122
negatives of kidney dialysis
-expensive for NHS -each session runs for couple of hours -uncomfortable experience -done regularly, multiple times a week
123
positive of kidney dialysis
-buy patient valuable time before donor organ found -readily available
124
negatives of kidney transplanted
-can be rejected by patient immune system -must take immunosuppressant drugs -often long waiting lists
125
what is added to blood in dialysis
-blood thinners to stop coagulation of blood outside body
126
what does dialysis fluid include
-same water, sugar, ion concentration as healthy blood -no urea
127
positives of kidney transplants
-permanent cure -no nedd to long hospital stay -no need to control diet
128
what do reproductive hormones cause in puberty
secondary sex characteristics to develop (facial hair, breasts)
129
on what day does ovulation occur
day 14
130
what is the duration of the menstrual cycle
28 days
131
what is ovulation
release of an egg
132
interaction of hormones in menstrual cycle
-F= FSH causes egg to mature, stimulates production of oestrogen -O= oestrogen stimulates release of LH, inhibits FSH -L= LH stimulates release of egg and progesterone -P= progesterone inhibits release of LH and FSH
133
role of FSH and where produced
-cause maturation of egg -produced in pituitary gland
134
role of oestrogen and where produced
-cause uterus lining to thicken -produced in ovaries
135
role of LH and where produced
-stimulates release of egg -produced in pituitary gland
136
role of progesterone and where produced
-maintains lining of uterus -produced in empty egg follicle
137
what happens when progesterone levels fall
-uterus lining breaks down
138
when does the uterus lining break downn
when no fertilised egg implants on uterus wall
139
stages of menstrual cycle
-stage 1= menstruation (4 days) -stage 2=uterus lining build up -stage 3= egge develops and released on day 14 -stage 4=wall maintained for 14 days until day 28, lining starts to break down again
140
methods of contraception x 7
-oral contraceptives -injection/ implant/ skin patch -barrier methods -intrauterine devices -spermicidal agents -abstaining from intercourse -surgical male and female sterilisation
141
how do oral contraceptives work
contain hormones to inhibit FSH production so no eggs mature
142
positives of oral contraceptives
-easily available -stops eggs maturing
143
negatives of oral contraceptives
-have to remember to take everyday -effectiveness affected by vomiting
144
how do injections/implants/ skin patches work
-slow release progesterone, inhibit maturation and release of eggs
145
positive of injection/implants/ patches
-lower dosage of pill=less side effects -implant left for multiple months or years
146
negative of injection/implant/patch
-cut into skin=risk of infection -have to go to gp
147
how do barrier methods work and examples
-diaphrams and condoms -prevent sperm form reaching egg
148
positives of barrier methods
-easily available -protect against STIs -often free
149
negatives of barrier methods
-short term and must be disposed -can break
150
how do inauterine devices work
-prevent implantation of embryo -or release a hormone (prevent egg maturation)
151
positives of IUDs
-one of most effective contraceptives -can be inserted any time of cycle -copper ones last many years
152
what do spermicidal agents do
-kill or disable sperm
153
positives of spermicidal agents
-if in condom, kill sperm even if it breaks
154
how does abstaining from intercourse work
-avoid sex before and after ovulation (when egg in oviduct)
155
negative of abstaining from intercourse
-lowest success rate -menstrual cycles vary
156
male surgical method of sterilisation name
vasectomy
157
what happens in a vasectomy
-sperm ducts cut and sealed
158
what happens in female sterilisation
-oviducts cut and sealed
159
positive of male and female sterilisation
-last a lifetime
160
negatives of sterilisation
-painful procedure -difficult to reverse -female sterilisation requires operation
161
ways of increasing fertility
-hormones in fertility drugs -IVF
162
how do fertility drugs work
-hormones FSH and LH given in fertility drug to women to stimulate ovulation
163
positive of fertility drug
result in pregnancy
164
negatives of fertility drug
-not always work (has to be done multiple times, expensive) -can stimulate too many eggs, multiple pregnancies
165
how does IVF work
-giving mother FSH and LH to stimulate maturation of several eggs -collect eggs from mother and fertilise by sperm from father in laboratory -fertilised develop into embryos -when they are tiny balls of cells, one or two embryos inserted into mother's uterus
166
positive of IVF
result in pregnancy
167
negatives of IVF
-very emotionally and physically stressful -success rates not high -multiple births can occur, high risk to mother and babies
168
when is adrenaline released
-when brain detects fear or stress, send nervous impulses to adrenal glands which secrete adrenaline
169
what does the 'fight or flight' response include
-increases heart rate -boosts delivery of oxygen and glucose to brain and muscles
170
what does thyroxine do in the body
-stimulates basal metabolic rate -stimulate protein synthesis for growth and development
171
define basal metabolic rate
speed at which chemical reactions occur in body at rest
172
what are thyroxine levels controlled by
negative feedback loop
173
what happens in the negative feedback loop of thryoxine
-level of thyroxine higher than normal detected -TSH (thyroid stimulating hormone) release from pituitary gland is inhibited -level of thyroxine in blood falls back towards normal
174
what causes more thyroxine to be released
-TSH =thyroid stimulating hormone
175
what is auxin and where found
-plant hormone -control growth of plant in response to light (phototropism) and gravity (gravitropism) -tips of shoots and roots
176
what does auxin do in the roots
-inhibits cell growth -more auxin on lower side due to gravity= cells on top elongate faster -root bends downards
177
how do shoots grow away from gravity
-gravity produces unqual distributionof auxin in tip, more auxin on lowr side -lower side grows faster, shoot bends upwards (negative gravitropism)
178
effect of auxin on shoots
encourages cell growth
179
what happens when a shoot is exposed to light
-more auxin on shaded side -cells grow (elongate) faster on shaded side -shoot bends towards light
180
practical for response of plant to varying light intensities
-pour fixed volume of water into 3 petri dishes and add cotton wool -place 10 seeds into each dish and place in warm location -allow seeds to germinate -place one dish in complete sunlight by window, second in partual sunlight and other in darkness in cupboard -use ruler to measure height of each seedling each day for a week in mm (hold up plant) -find mean height of seedlings each day and compare
181
control variables for platn responses to light practical
-number of seeds -type of seed -volume of water -temperature
182
commercial uses of auxin and how they work
-weed killer ( disrupt normal growth patterns) -growing from cutting with rooting powder (produce clones of plant quickly) -growing cells in tissue culture (grow clones by stimulating cells to divide to form roots and shoots)
183
what does giberellins do and use in agriculture
-initiate seed germination -induce flowering -grow larger fruit
184
what is ethene and what is it used for
-gas, controls cell division and ripening of fruits -used to speed up ripening of fruits in transport
185
use of nutrients in plants
-making chlorophyll -making protein/amino acids -for respiration
186
what are the male and female gametes in animals
sperm and egg cells
187
what are the male and female gametes in flowering plants
pollen and egg cells
188
who investigated inheritance
Mendel
189
what did gregor mendel do to investigate genetic inheritance
cross pea plants
190
define phenotype
physical characteristics of an organism
191
define genotype
collection of genes/alleles for a particular trait
192
define allele
different forms of the same gene
193
what must happen with recessive alleles to be expressed
allele must be present on both chromosomes
194
what must dominant alleles be to be expressed
present on at least one chromosome
195
define homozygous
when alleles are both identical for same characteristic
196
define heterozygous
two different alleles for characteristic
197
chromosomes of boy
XY
198
chromosomes of girl
XX
199
mitosis daughter cells
two genetically identical daughter cells
200
purpose of mitosis
produce identical cells for growth and repair
201
number of cell divisions in mitosis
1
202
meiosis daughter cells
4 genetically different daughter cells
203
number of chromosomes in mitosis daughter cells
46
204
number of chromosomes in meiosis daughter cells
23
205
number of cell divisions in meiosis
2
206
speed of mitosis reproduction
FAST
207
speed of meiosis reproduction
SLOW
208
why does mitosis not increase chance of species survival
as if a new disease or change in environment affects an individual, as all the cells are clones they will all be affected
209
why does meiosis increase chance of species survival
as there in genetic variation in the population, allows natural selection to take place and evolution
210
what is meiosis used for
producing gametes
211
where mitosis occurs
-bacteria= binary fission -humans=everywhere except in sex organs
212
where meiosis occurs
-sex organs (testes and ovaries)
213
where does mitosis occur in plants
meristem cells in tip of roots and shoots
214
what does asexual reproduction involve
-1 parent -no fusion of gametes -mitosis -produce clones
215
why is asexual reproduction quicker
-no need to find mate -produces large number of offspring
216
why is sexual reproduction slower
-have to find mate -few offspring produced
217
advantages of sexual reproduction
-produce variation in offspring -if environment change theres survival advantage due to variaiton by natural selection -natural selection sped up by humans through selective breeding (increase food production)
218
advantages of asexual reproduction
-faster than sexual -only one parent needed -time and energy efficient as no mate needed -many identical offspring produced in favourable conditions
219
how do malarial parasites reproduce
-asexually in human host -sexually in mosquito
220
how do fungi reproduce
-asexually by spores -sexually to give variation
221
how do plants reproduce
-seeds produces sexually -reproduce asexually by runners in strawberry plants (side shoot goes into ground, takes roots, forms clone) -daffodils reproduce asexually by bulb division
222
process of meiosis
-cells in reproductive organs copies of genetic info made -cell divides twice to form four gametes with 23 chromosomes each -genetically different
223
what happens at fertilisation
-gametes join, restore full number of chromosomes (46) -new cell divides by mitosis= increase cells -as embryo develops, cells differentiate
224
how many sets of chromosomes do body cells have
two sets
225
how many sets of chromosomes do sex cells have
one set
226
define germination
process where plant grows from seed
227
number of chromosomes in nucleus
46
228
what does dna stand for
deoxyribonucleic acid
229
what is DNA
chemical composing all genetical material in a cell
230
where is dna contained
in chromosomes
231
what is DNA material wise and its structure
-polymer -two strands coiled to form a double helix
232
define gene
small section of DNA on a chromosome
233
what does each gene code for
particular sequence of amino acids to make specific protein
234
what do gene tell cells
what order to make put amino acids together in
235
what does DNA determine
-what proteins the cell produces -therefore what type of cell it is ( red blood cell produce haemoglobin, skin cell produce keratin)
236
define genome
entire set of genetic material of an organism
237
how does understanding the entire human genome help
-use in tracing human migration patterns of past (see where new populations split) -search for genes linked to different types of inherited disease -understand and develop new effective treatments for inherited disease
238
what are the monomers that make up DNA
nucleotides
239
what do nucleotides consist of
-one phosphate molecule -one sugar molecule -one base
240
what are the four bases and their pairs
Adenine-Thymine Guanine-Cytosine
241
what is the code for an amino acid
sequence of 3 bases
242
what do non-coding prts of DNA do
control whether or not a gene is expressed (switch genes on and off)
243
what is DNA made up of
repeating nucleotide units
244
what is the the ‘backbone’ of DNA called
sugar-phosphate backbone
245
shape of DNA
double helix
246
where are proteins made
in ribosomes contained in cell cytoplasm
247
what happens in protein synthesis
-two nucleotide DNA polymers seperate -enzyme copies code of DNA on template strand to form mRNA strand with complimentary bases to template strand -small enough to leave nucleus and go to ribosome -sequence of bases are read by ribosome -amino acids brought down by carrier molecules (have anti codons) -ribosomes join chain of amino acids in correct order -when chain is complete, folds up to form unique shape -enable to do job
248
different functions of proteins
-enzymes= biological catalysts speed up chemical reactions in body -hormones= carry messages around body -structural proteins= collagen, strengthen tissues
249
what do variations in non-coding parts of DNA cause
-affect how genes are expressed
250
how often do mutations occur
continuously
251
what do most mutations do
most do not alter proteins, or alter slightly so appearance and functions not changed
252
what do a few mutations code for and how does this affect enzymes
-an altered protein with different shape -enzyme no longer fit substrate binding site
253
what happens when mutations occurs to structural proteins
may lose their strength, no longer provide structure and support
254
define mutation
change in gene or chromosome
255
what are most characteristics a result of
multiple genes interacting
256
what do genetic diagrams show
possible alleles of offspring
257
two inherited disorders
-Cystic Fibrosis -Polydactyly
258
what is cystic fibrosis caused by
recessive allele
259
what is polydactyly caused by
dominant allele
260
effects of cystic fibrosis
-thick sticky mucus in pancreas and air passages
261
effects of polydactyly
extra fingers or toes
262
what is cystic fibrosis a disorder of
genetic disorder of cell membranes
263
what is an inherited disorder
condition caused by genetic change passed on from parents to offspring
264
what is cystic fibrosis caused by
mutation in protein in cell membranes (responsible for viscosity of mucus)
265
what can embryos be screened for
genetic disorders
266
what is analysed for disorders in IVF
DNA of IVF embryo cell
267
arguments for embryo screening
-prevents suffering due to disorders -less money has to be spent by government and tax payers on treatment for disorders -there are laws to prevent destroying embryos based on sex for example
268
arguments against embryo screening
-implies people with genetic disorders are undesirable (prejudice) -screening is expensive -may be a point where people screen embryos for characteristics such as hair colour -destroying embryos is unethical and screening can damage healthy individuals
269
what is done for embryo screening
-cell removed from each IVF embryo -genes analysed
270
what three conclusions did mendel reach
-characteristics determined hy hereditary units -hereditary units passed on to offspring unchanged from both parents (one from each) -hereditary hnits can be dominant or recessive
271
why did it take a while for people to understand mendels work
-no idea of genes, DNA or chromosomes
272
define variation
differences in characteristics of individuals in population
273
what can variation be caused by
DIFFERENCES IN: -genes inherited -conditions in which they have developed (environment) -combination of both
274
what is there usually in a population
genetic variation
275
what is variation a result of in terms of DNA
constant, random mutations in DNA
276
define species
group of organisms with similar characteristics that can breed to produce fertile offspring
277
examples of variation caused by genes passed down
-eye colour -sex -dimples
278
examples of variation caused by environmental AND genetic causes
-height -weight
279
examples of variarion caused by environmental causes
-accent -tan
280
how does natural selection occur
-variation existing in population -due to mutations (random, continuous changes in DNA) affecting characteristics -individuals with characteristics most suited to environment survive (survival of the fittest) -survivors have more chance of reproducing -offspring inherit the characteristics most suited to environment -organisms less suited to environment= less likely to survive -over time characteristics most suited to environment become more common and species evolves
281
what is the theory of evolution
all species of living things evolved from simple life forms that first developed over three billion years ago
282
what happens if the phentoypes of two populations of one species becomes too different
can no longer interbreed to produce fertile offspring, form two new species
283
what is evolution
change in inherited characteristics of population
284
when does natural selection occur
when mixed population faced with environmental challenge, some versions of gene more advantageous
285
what is selective breeding
humans breed plants and animals for particular generic characteristics
286
what does selective breeding involve
-choose parents with desired characteristic from mixed population -bred together -from offspring those with desired characteristic bred together -continues over many generations until all offspring show desired characteristic
287
4 examples of chosen characteristics in selective breeding
-disease resistance in food crops -animals to produce more meat or milk -domestic dogs with gentle nature -large or unusual flowers
288
what is a negative of selective breeding
-can lead to inbreeding ( some breeds prone to disease or inherited defects)
289
how does selective breeding affect gene pool of species
reduces variation in species
290
why is a reduced gene pool bad
-more difficult for species to adapt to environmental changes
291
define genetic engineering
-modifying genome of organism by introducing gene from another organism to give desired characteristic
292
examples of genetic engineering
-plant crops genetically engineered to be resistant to disease or produce bigger fruits -bacterial cells genetically engineered to produce useful substances like human isnulin to treat diabetes
293
what are GM crops
crops that have had their genes modified through genetic engineering
294
benefits of genetic engineering
-increased yield -crops resistant to insect attack or herbicides
295
negatives of genetic engineering
-effects of eating GM crops on human health not fullt explored or understood -affects number of wild flowers and crops and populations of insects (decreased biodiversity) -transplanted genes can get into environment, picked up by weeds
296
example of GM crop specific
Golden Rice= contains nutrient to help with sight
297
what is a future medical possibility of genetic modification
-overcome some inherited disorders
298
process of genetic engineering
-enzymes used to isolate desired gene -inserted into vector (bacterial plasmid or virus) -vector used to insert gene into required cells -genes transferring at early stage if development to develop with desired characteristics
299
what is a clone
individual produced asexually and is genetically identical to parent
300
what is tissue culture
using small groups of cells from part of plants to grow identical new plants
301
what is tissue culture used for
-preserving rare species of plants -commercially im nurseries
302
what is the process of cuttings
-older simple method used by gardeners to produce many identical new plants from parent plant -take cutting from original parent plant -placing cutting in hormone rooting powder (auxin) and compost -plant grows into mature plant genetically identical
303
limitation of using cuttings
-can only clone one plant from one cutting
304
how does the process of tissue culture work
-few cells scraped off parent plant -put into growth medium with auxin and nutrients -cells divide by mitosis -differentiate into range of tissues types into plantlets -can be transferred carefully into compost, grow into many clones
305
negative of usinf tissue culture
-must be done under sterile conditions or there is risk of infection from disease
306
what is embryo cloning
-animals given fertility hormones to produce many eggs -eggs fertilised in womb using sperm from prize bull -embryo can be washed out of womb, contain desires genes -embryos split into individual cells ( by mitosis) -produce many embryos -embryos transferred to wombs of surrogate cows, develop into cows that are identical
307
negative of embryo transplants
-expensive -no guarantee that embryo is worth it as the genotype is not guaranteed
308
advantages of embryo transplants
-allows good cows to produce alot more offspring that it could
309
process of adult cell cloning
-nucleus removed from unfertilised egg cell -nucleus from adult body cell inserted into egg cell -electric shock stimulates egg cell to divide to form embryo -embryo cells contain same genetic informarion as adult skin cell -embryo develop into ball of cells, inserted into womb of adult female to continue development
310
issues of cloning
-reduced gene pool -cause inherited diseases -may be unsuccesful
311
advantages of cloning
-protect endangered species -lead to greater understanding of development of embryo
312
who proposed the theory of evolution
charles darwin
313
why was the theory of evolution by natural selection only gradually accepted
-challenges idea that god made all animals and plants living on earth -insufficient evidence at the time to convince scientists -inheritance and variation not known until years after theory published
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what are organisms with the most suitable characteristics to the environment
more successful competitors
315
three scientists that proposed ideas on evolution, speciation etc
-charles Darwin -Lamarck -Alfred Russel Wallace
316
what did lamarck propose
-changes that occur in organism during its lifetime can be inherited
317
why was lamarcks theory rejected
-experiments didnt support his hypothesis
318
what has the theory of evolution been developed by
-new discoveries about variation, inheritance and mutations
319
define speciation
-development of a new species due to change of phentotypes
320
when does speciation occur
-populations of same species change enough that they cannot interbreed to produce fertile offspring
321
define extinction
no surviving individuals of a species remaining
322
causes of extinction
-quick environment changes (too quick for evolution of species) -new predator -new disease -new competitor -catastrophic event
323
process of speciation
-two populations of same species isolated (seperated) -due to physical barrier (conditions on either side slightly different) -populations adapt to new environments through natural selection (alleles of beneficial characteristics passed down) -individuals from different populations changed so much that they can no longer breed to produce fertile offspring= seperate species
324
who came up with the theory of speciation
Alfred Russel Wallace
325
what did wallace independently come up with
idea of natural selection
326
how did darwin and wallace develop the theory of evolution by natural selection
-publish joint writings -darwin published On the Origin of Species -wallace gathered evidence for evolutionary theory ( warning colouration)
327
factors of speciation
-isolation -natural selection
328
how did our understanding of genetics develop
-mendel carried out breeding experiments( discover hereditary units passed onto inheritors unchanged, determine characteristics) -behaviour of chromosomes in cell division observed
329
when did mendel carry out breeding experiments
mid 19th century
330
when was the behaviour of chromosomes observed
late 19th century
331
what were the hereditary units in mendels discovery
genes
332
when was the structure of DNA determined and mexhanism of gene function
mid 20th century
333
why was mendels discovery not recognised until after his death
-no knowledge of genes, DNA, chromosomes
334
what was discorvered in the early 20th century
similarities in how chromosomes and mendels ‘units’ behaved
335
what is evidence for natural selection by evolution
-fossils -antibiotic resistance in bacteria
336
why is the theory of evolution now accepted
-evidence available to show that characteristics are passed on to offspring in genes
337
define a fossil
remains of organisms from millions of years ago found in rocks
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how are fossils formed
-bones, teeth, shells which do not decay easily are buried -replaced with minedals overtime forming hard rock like substance in same shape -soft tissues and organs of organisms decay -fossil remains in rock and is dug up
339
3 examples of fossils
-gradual replacement by minerals -casts and impressions -preservation
340
how are fossils formed from preservation
-no oxygen or moisture so decay microbes cant survive in amber -glaciers is too cold for decay microbes to function -peat bogs too acidic for decay microbes to survive
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what do fossils show
how much or little different organisms have changed as life developed on Earth
342
why is the fossil record incomplete
-many earlier forms of life were soft bodies, decayed completely and didnt form fossils and left few traces -traces destroyed by geological activity
343
why are scientists uncertain about how life began on earth
fossil record in incomplete
344
how can fossils be dated
-radioactive dating rocks surrounding the fossils
345
why can bacteria evolve rapidly
-reproduce at fast rate -binary fission occurs every 20 minutes
346
process of antibiotic resistance
-mutations cause new strains of antibiotic resistant bacteria to arise -some strains are resistant and are not killed in bacteria population whilst non-resistant are killed -resistant bacteria survive and reproduce rapidly, population of resistant strain increases -resistant strain spreads as people not immune, no effective treatment
347
what is an example of an antibiotic resistant bacteria
MRSA in hospitals
348
what can be done to reduce rate if antibiotic resistance
-doctors not prescribe antibiotics inappropriately (for viral or non serious infections for eg) -patients should complete full course of antibiotics so none survive and mutate to form resistant strains -agricultural use of antibiotics restricted
349
how can the development of new antibiotics be described
-costly -slow
350
what have living things been classified into groups by
-structure -characteristics
351
what are organisms named by
-binomial system of genus and species
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who classified species into the linnaean system
Carl linnaeus
353
what is the linnaean system organised into
-Kingdom -Phylum -Class -Order -Family -Genus -Species
354
why did classification systems change over time
-evidenxe of internal structures more developed due to microscope improvements -more understanding of biochemical processes -new models of classification proposed
355
what did carl wowse propose
three-domain system
356
which scientists came up with models of classification
-Carl Linnaeus -Carl Woese
357
what did carl woese use evidence from
-new chemical analysis techniques
358
what is the three domain system divided into
-archaea -bacteria -eukaryota
359
what are archaea
primitive bacteria usually living in extreme environments
360
what are bacteria
true bacteria
361
what do eukaryota include
-protists -fungi -plants -animals
362
example of binomial naming system
Homo sapiens
363
what do evolutionary trees show
how organisms are believed to be related
364
what do evolutionary trees use as evidence
-current classification data for living organisms -fossil data for extinct organisms
365
what specifically do evolutionary trees exhibit and how is this helpful
-common ancestors between species (more recent common ancestor= more closely relates species= more characteristics likely to be shared)
366
define a habitat
place where organisms live
367
define population
all organisms of one species living in a habitat
368
define community
populations of different species living in one habitat
369
what are abiotic factors
non living factors of environment
370
define biotic favtors
living factors of environment
371
define ecosystem
interaction of community of living organisms interacting with non living parts of environment
372
what do organisms need resources for
to survive and reproduce
373
what do plants compete with each other for
-light -space -water -mineral ions from soil
374
what do animals compete with each other for
-food -mates -territory
375
what do species depend on others for
-food -shelter -pollination -seed dispersal
376
what does interdependence mean
any major change can have far reaching effects
377
what happens if one species is removed
affects the whole community
378
what is a stable community
one where all species and environmental factors in balance, population size remains constant
379
examples of abiotic factors x7
-moisture level -light intensity -temperature -carbon dioxide level -wind intensity -oxygen level -soil pH and minerals
380
what could a decrease in mineral content cause
nutrient deficiencies
381
what could a decrease in light intensity, temperature or level of carbon dioxide cause
decreased rate of photosynthesis, less plant growth, population size decrease
382
examples of biotic factors x 4
-new predators -competition -new pathogens -availibility of food
383
define interdependence
when all species in a community depend on one another for survival and any change affects many diff species
384
why does competition lead to population decrease
species is outcompeted for resources needed to survive and develop, so numbers are insufficient to breed
385
types of adaptations
-structural -behavioural -functional
386
example of structural adaptation
camel having large surface area to volume ratio to lose heat
387
example of behavioural adaptation
migrating during the winter
388
example of functional adaptation
-bears hibernating in winter, lower metabolism, conserve energy -camel humps store fat to metabolise later when there is lack of food in desert
389
example of extremophiles
-bacteria living in deep sea vents
390
aspects of extreme environments
-high temperatures -high salt concentration -high pressure
391
what are extremophiles
microorganism like bacteria that are adapted to live in very extreme conditions
392
examples of plant adaptations
-cacti having spines and thick stems, wide shallow roots -sunken stomata to limit transpiration (loss of water) -space, some seeds have propellers to distribute, produce fruit to be eaten and defecated elsewhere
393
why can’t most living things live in very hot conditions
temperature too high, denatures enzymes
394
why are extremely salty environments bad for organisms
-upset osmotic balance
395
what are producers and why
-photosynthetic organisms (plants) that produce their own food (glucose) -producers of biomass for rest of life on earth
396
what is transferred when organisms are eaten
energy
397
what is used to measure abundance of organisms
quadrats
398
what is used to measure distribution of organisms along a line
transects
399
what are predators
consumers that kill and eat other animals
400
what is prey
animals that are killed and consumed by other animals (predators)
401
what materials are cycled in an ecosystem
-water -carbon
402
what do environmental changes affect
distribution of organisms ( where they live)
403
what can affect change in distribution of organisms
-change in water availability -change in temperature -change in composition of atmospheric gases
404
what are different materials cycled through
abiotic and biotic components of ecosystem
405
explain the steps of the water cycle
-energy from sun cause water evaporation from land and sea, turn to vapour+ water evaporate from plants (transpiration) -warm water vapour rises, cools and condense form clouds -water fall as precipitation onto land, fresh water provided for plants and animals -drain into sea, repeats
406
two types of decay organisms
-detritus feeders -fungi
407
what does cycling of materials provide
building blocks for future organisms
408
what do plants turn elements into and examples of these elements (from where)
-complex compounds -carbon, hydrogen oxygen, nitrogen -from soil and air
409
factors that affect decay
-warmer temperature -aerobic conditions -moist
410
where does CO2 enter in the leaves
stomata
411
three main processes in carbon cycle
-photosynthesis -respiration -combustion
412
steps of carbon cycle
-CO2 from air taken in by plants through stomata for photosynthesis -carbon used to make carbon compounds like glucose, turned into carbs, fats, proteins etc (-plants respire, return carbon to atmosphere as CO2) -eaten by animals, glucose used as fuel, some carbon is part of proteins and fats in body, animals respire (release CO2 back into atmosphere) -plants, algae, animals die (provided conditions for decay are optimal), detritus feeders and bacteria and fungi can feed on remains, respire to break down (release CO2) -animals produce waste (feces, urine) also broken down, return nutrients back to soil -no decay= fossils= fossil fuels (coal, natural gas etc), burned = combustion in power stations (release CO2 in air)
413
what is a human activity affecting the carbon cycle
combustion of fossil fuels in power stations
414
what happens when aquatic animals respire
carbon dissolved in oceans
415
what are examples of carbon sink
-fossils containing carbon trapped in sedimentary rock -carbon dissolved in oceans
416
define carbon sink
large amounts of carbon locked up
417
how can nitrates be recycled
-dead plant/ animal decomposes -by decomposerssuch as detritus feeders and bacteria and fungi -releases mineral ions into soil -mineral ions taken in by plants through roots
418
examples of decomposers
-detritus feeders -bacteria -fungi
419
conditions affecting rate of decay and why
-warmer temperatures for optimum enzyme activity, not too much that denatures -oxygen availibility for respiration (aerobic conditions) -water availability for biological processes -number of decay organisms for faster decomposition
420
how is biogas made
-anaerobic decay of waste material
421
what is compost used by farmers as
natural fertiliser for growing garden plants or crops
422
what is biogas mainly made up of
methane
423
why is biogas produced
to be burned as a fuel to release energy
424
where is biogas (methane gas) produced
in biogas generators
425
how are optimum conditions provided for decay by farmers
-compost bins -decaying materials (food, grass) -opening for oxygen (aerobic decay) and bacteria, detritus feeders added -water added -temperature increases due to aerobic activity of feeders producing heat (may be insulated in winter) -circulated by stirring, distribute oxygen and feeders -produces sludge used as fertiliser
426
aspects of simple biogas generator
-inlet for waste materials -food and waste material digested by decomposes -made air tight for anaerobic decay -methane gas produced, collected from biogas outlet -outlet for digested material
427
negative of biogas generation
-cant be stored as liquid -must be used instantly -generator need to be kept at constant temp
428
what three things can environmental changes be
-seasonal -geographic -caused by human interaction
429
define biodiversity
variety of all different species of organisms on earth or in ecosystem
430
what does great biodiversity ensure
-stability of ecosystems -reduce dependence of one species on another for food, shelter and maintenance of physical environment
431
examples of geographic environmental changes
-water availability -salinity -altitude
432
examples of seasonal environmental changes
-species migrate or hibernate -different regions (tropical, temperate ) with different seasons
433
examples of human caused environmental changes x4
-air pollution -acid rain -global warming -industry and farming cause water pollution
434
indicator species for air pollution and what this shows
-bushy lichen= clean air -leafy/ crusty lichen= polluted air
435
indicator species for water and what they show
-stonefly nymph/ fresh water shrimp= clean -sludge worm/ red tailed maggot= high pollution
436
environmental impacts of human population growth due to pollution
-water pollution=from sewage, fertiliser, toxic chemicals -air pollution from smoke and acidic gases -land= from landfill and toxic chemicals
437
what does pollution do
kills plants and animals, reduces biodiversity
438
why is consumption of resources increasing
-standard of living increases -more resources used due to increase in demand, more finite materials used to generate energy for manufacturing
439
what contributes to global warming
-increasing levels of carbon dioxide and methane in the atmosphere, thickens green house gas layer= less of suns trapped energy radiated back into space
440
consequences of global warming
-ice to melt and seawater expands= sea level rise, flood low level land (lose habitats) -distribution of animals change as temp increase -change in migration patterns -reduction in biodiversity
441
why is the human population increasing rapidly
-modern better medicine -improved farming methods (less hunger and people dying from disease)
442
define eutrophication
-pesticides and herbicides wash into water -increased nutrient fertilisers means algae form bloom over water surface -less sunlight reach other water plants -plants die and they cannot carry out enough photosynthesis without light -bacteria etc increase and decompose dead plants, using up and reducing oxygen in water during respiration -low oxygen levels cause insects and fish to suffocate (die)
443
what is it called when nitrate fertilisers are washed into waterways
leaching
444
what do humans use land for
-farming -dumping waste -building -quarrying
445
examples of human land use with bad environmental effects
-deforestation -destruction of peat bogs
446
what is deforestation
large scale clearing of trees
447
why does deforestation take place
-clear land for farming cattle -grow crops for biofuels
448
effects of deforestation
-less carbon sink as trees removed -more CO2 into atmosphere as trees burned to clear land + decomposes respire when feed on dead wood -less biodiversity as less habitats, species extinct
449
what are peat bogs
-areas of land that are acidic and waterlogged -plants don’t fully decay due to lack oxygen, partly rotted plant build up form peat -carbon stored
450
what happens when peat bogs are drained
-peat contact with air, microorganisms decompose it, release CO2
451
negatives of destroying peat bogs
-habitats destroyed -peat burned as fuel= release CO2
452
why are peat bogs cleared
-use peat as fuel -farmland -compost
453
define bioaccumulation
toxins from fertilisers and pesticides build up in food chain and affect organisms
454
programmes to reduce negative effects of humans on ecosystems x5
-breeding programmes endangered species -protection of rare habitats -reintroduce field margins and hedgerows in agricultural areas where one type crop grown ( habitats) -reduce deforestation and co2 emissions policies -recycle resources, less waste dump in landfill
455
difficulties in maintaining biodiversity x 3
-costs money -some people can lose jobs (tree chopping, logging) -some organisms seen as pest by farmers
456
tropic level 1
producers (plants and algae) that make own food
457
tropic level 2
herbivores, primary consumers
458
tropic level 3
carnivores that eat herbivores (secondary consumers)
459
trophic level 4
carnivores eat other carnivores (tertiary consumers)
460
define apex predators
carnivores with no predators
461
how do decomposers break down waste
-bacteria and fungi decompose dead matter -secrete enzymes into environment -break down into small soluble food molecules, diffuse into microorganism
462
what happens when you move up a tropic level
-less energy -less biomass -fewer organisms
463
what is lost between each tropic level
biomass
464
how much energy is transferred from light from the sun for photosynthesis by producers
0.01
465
how much biomass is transferred to each tropic level
0.1
466
why is biomass lost between trophic levels
-not all ingested material absorbed, some egested as faeces -not all of organism eaten (e.g bones, some plant material) -biomass converted to other substances lost as waste e.g glucose in respiration
467
how to calculate efficiency of biomass transfer
(biomass transferred to next / biomass available at previous) x 100
468
define food security
having enough food to feed a population
469
biological factors affecting food security x6
-birth rate increase -changing diets developed countries (scarce food made more scarce) -new pests and pathogens affect farming -conflict affect water and food availability -cost of agricultural input like machinery -environment changes cause famine if less rain
470
what decreases fish stocks
overfishing
471
sustainable ways to maintain fish stocks
-fishing quotas -net size
472
why is it important to maintain fish stocks
some species might disappear due to less breeding
473
what are fishing quotas
limits on number and size fish caught in certain areas prevent overfishing
474
how do net sizes help in sustainable fisheries
bigger mesh size means younger fish slip through, reach breeding age ,maintain population
475
how can food production be made more efficient
-limit movement ( chickens kept in small pens) less energy used moving and fish farmed in cages -kept in temperature controlled environment, less transfer of energy to control body temp -more energy available for growth -animals fed high protein food
476
objections against factory farming
-disease spread easily -ethical = unnatural, uncomfortable -use of antibiotics in cattle cause antibiotic resistance
477
why is efficient farming helpful
means more energy available for growth in organisms
478
example of biotechnology for food
-fungus Fusarium produce mycoprotein -grown in aerobic conditions on glucose syrup -biomass harvested and purified to produce mycoprotein
479
what is mycoprotein used for
produce high protein meat substitute for vegetarians
480
why are modern biotechnological techniques beneficial for food
large amounts of microorganisms can be cultured for food under controlled conditions
481
process of genetic engineering of bacteria to produce insulin
-plasmid removed -insulin gene cut out human chromosome using restriction enzymes leaving with ‘sticky ends’ -bacterial plasmid cut open using same enzyme, leaving the same sticky ends -plasmid and human insulin gene joined together by DNA ligase enzyme -ends joined to form molecule of DNA -recombinant plasmid inserted into bacterial cell -bacteria reproduce, plasmids are copied, all express human insulin gene and produce human insulin protein -grown in vat under controlled conditions -insulin harvested and purified, treat diabetics
482
example of GM crop
golden rice
483
benefits of GM crops
-resistance to pests=increase crop yield -more nutritional value eg golden rice= vitamin a= aid eyesight
