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Biology > Paper 2 Major focus > Flashcards

Paper 2 Major focus Flashcards

1
Q

Control of body temperature

When too high

A
  • Temperature receptors detect that core body temperature is too high
  • Thermoregulatory centre acts as a coordination centre
  • Effectors carry out response :
    1) Sweating - transfer energy to the environment
    2) Skin hair lay flat - no air is trapped to insulate the skin
    3) Vasodilation - blood vessels supplying the skin dilate so more blood flows close to the surface so more heat is transferred from the skin to the environment
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2
Q

Control of body temperature

When too low

A
  • Temperature receptors detect that core body temperature is too high
  • Thermoregulatory centre acts as a coordination centre
  • Effectors carry out response :
    1) No sweat is produced - less energy is transferred to the environment
    2) Skin hair stand up - air is trapped to insulate the skin
    3) Vasoconstriction - blood vessels supplying the skin constrict so less blood flows close to the surface so less heat is transferred from the skin to the environment
    4) Start shivering, muscles move so more respiration occurs and this releases energy and heat
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3
Q

Control of blood glucose concentration

A

When too high :
- Pancreas releases insulin
- Insulin goes to the target organ which is the liver and stimulates the liver to convert the excess glucose into glycogen
When too low :
- Pancreas releases glucagon
- Glucagon goes to the target organ which is the liver and stimulates the liver to convert glycogen into glucose

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4
Q

Type 1 diabetes

A

Type 1 - Genetics
- Pancreas produces little or no insulin, so high blood glucose levels and this leads to the kidney excreting the glucose of urine, producing lots of urine causing
the person to become thirsty
- Also become tired and loose weight due to glucose not being taken into cells
- Have to take insulin therapy
- Limiting the intake of simple carbohydrates
- Regular exercise to remove excess glucose

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5
Q

Kidney

Urea

A
  • Urea - amino acids cannot be stored by the body so any excess amino acids are converted into fats and carbohydrates
  • Ammonia is produced as a waste product of this processed which is called deamination
  • Ammonia is toxic so it is converted into urea in the liver, and is transported to the kidney where it is filtered out and excreted from the body in the urine
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6
Q

Kidney

Ions

A
  • Ions such as sodium are taken into the body in food then absorbed into the blood
  • If the ion content of the body is wrong, this could upset the balance between ions and water, means too much or too little water is drawn into cells by osmosis
  • Some ions are lost in sweat, however this is not regulated, so the right balance of ions in the body must be maintained by the kidneys and the right amount of ions is reabsorbed into the blood after filtration and the rest is removed in urine
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7
Q

Kidney

Water

A
  • Water is lost from the skin when sweating and from the lungs when breathing out
    When water level is too high (Opposite response when too low)
    1) A receptor in the brain detects that the water content is too high
    2) Coordination centre in the brain receives this information
    3) Pituitary gland releases less ADH so less water is reabsorbed from the urine in the kidney
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8
Q

Type 2 diabetes

A

Type 2

  • The body doesn’t respond to the insulin the pancreas produces
  • Blood sugar level rises
  • Being overweight and having a lack of exercise increases risk of type 2
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9
Q

Auxin

A
  • Is a plant hormone that controls growth near the tips of shoots and roots
  • It controls the growth of a plant response to light (phototropism) and gravity (gravitropism)
  • Auxin is produced in the tips and moves backwards to stimulate the cell elongation (enlargement) process which occurs in the cells behind the tips
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10
Q

Shoots grow towards light

A
  • When a shoot tip is exposed to light, more auxin accumulate on the side that is shaded
  • This makes the cells grow faster on the shaded side so the shoot bends towards the light
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11
Q

Investigate Plant Growth Responses

A

Independent variable - Light intensity
Dependent variable - Height of seedling
Control variable - Volume of water/type of seed/number of seedling
1) Place cotton wool in petri dish and soak them in equal volume of water
2) Leave the dishes in a warm area, and water them everyday with the same amount of volume
3) The seed will germinate
4) Make sure same number of seedling in the all 3 petri dishes, if not remove excess numbers
5) Measure height of seedling, make sure the stem is straight
6) Place dishes into different conditions : One is in full sunlight. One is partially light. One in a dark room
7) Measure the height of seedling every day.

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12
Q

Gibberellin

A
  • Stimulate plant stems to grow
  • Controlling dormancy - lots of seeds won’t germinate until they been through certain condition
  • Inducing flowering - require certain condition to flower
  • Growing larger fruit - seedless varieties
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13
Q

Ethene

A
  • Stimulates ripening of fruits
  • Influences the growth of the plants by controlling cell division
  • Speed up ripening
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14
Q

Sexual Reproduction

A
  • Produces genetically different cells
  • Genetic information from two organisms
  • Mother and father produce gametes - egg and sperm cells
  • Gametes contain 23 chromosomes
  • Egg and the sperm cells then fuse together to form a cells with a full number of chromosomes
  • Mixture of genetic information produces a variation in the offspring
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15
Q

Asexual Reproduction

A
  • Only one parent and genetically identical
  • Happens by mitosis
  • New cell has the exactly same genetic information as the parent cell - clone
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16
Q

Meiosis

A
  • Gametes are produced by meiosis
  • Before cell starts to divide, it duplicate its genetic information
  • In the first division in meiosis the chromosome pair line up in the centre of the cell
  • The pairs are then pulled apart so each new cell only has one copy of each chromosome
  • In the second division the chromosomes line up again in the centre of the cell and the arms of the chromosomes are pulled apart
  • You get four gametes each with only single set of chromosomes and each gamete is genetically different
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17
Q

DNA

A
  • Deoxyribonucleic acid
  • Contain coded information
  • Found in chromosomes
  • DNA is a polymer - two strands - double helix structure
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18
Q

Gene

A
  • Small section of DNA on a chromosomes
  • Each gene codes for a particular sequences of amino acids which are put together to make a specific protein
  • Genes tells cells what order to put amino acids
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19
Q

Genome

A
  • Entire set of genetic material of an organism
  • It allows scientist to identify genes in the genome that are linked to different type of disease
  • Knowing which genes are linked to inherited disease could help us to understand them and develop effective treatments
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20
Q

Structure of DNA

A
  • DNA strands are polymers made up of lots of repeating units called nucleotides
  • Each nucleotide consists of one sugar molecule, one phosphate molecule and one base
  • Sugar and phosphate molecules in the nucleotides form a backbone to DNA strand. The sugar and phosphate molecules alternate
  • The bases of A,T,C,G
  • A links with T / C links with G (commentary base pairs)
  • Order of bases in a gene decides the order of amino acids in a protein
  • Each amino acids coded for by a sequence of three bases in the gene
  • Amino acid join together to make various proteins depending on the order of the gene bases
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21
Q

Protein synthesis

A
  • Genes in the DNA produced a template for the protein and the template reflects the sequences of bases in the DNA but small enough to leave the nucleus
  • Template leave the nucleus and binds to the surface of a ribosome
  • Cytoplasm contains carrier molecules each attached to a specific amino acid and the carrier molecules attached themselves to the template in the order given by the DNA
  • Amino acid are joined together to form a specific protein
  • Carrier molecules brings keep bringing specific amino acids to add to the growing protein chain in the correct order until the template is completed
  • The protein detaches from the carrier molecules and the carrier molecules detach from the template and return to the cytoplasm to pick up more amino acids
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22
Q

Cystic Fibrosis

A
  • Caused by a recessive allele
  • Genetic disorder of the cell membrane and results in the body producing a lot of thick sticky mucus in the air passages and in the pancreas
  • People with one copy of the allele won’t have the disorder - carriers
  • For a child to have the disorder - both parents must be either carries or have the disorder themselves
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23
Q

Polydactyly

A
  • Caused by a dominant allele
  • Born with extra fingers or toes
  • Can be passed on if one parent is affected
24
Q

Gamete

A
  • Reproductive cell
25
Q

Chromosome

A
  • Section of DNA
26
Q

Gene

A
  • Codes for a specific protein
27
Q

Allele

A
  • Different forms of the same gene

- Code for different protein

28
Q

Dominant allele

A
  • Expressed if one allele is present
29
Q

Recessive allele

A
  • Expressed only if homozygous
30
Q

Homozygous

A
  • Two identical alleles
31
Q

Heterozygous

A
  • Different alleles
32
Q

Genotype

A
  • Genetic make up
33
Q

Phenotype

A
  • Physical appearance
34
Q

Abiotic factors

A
  • Non living factors which affect a community
  • Light intensity
  • Temperature
  • Moisture levels
  • Soil ph and mineral content
  • Wind intensity and direction
  • Carbon dioxide levels for plants
  • Oxygen levels for aquatic animals
35
Q

Biotic factors

A
  • Living factors which affect a community
  • Availability of food
  • New predator
  • New pathogens
  • One species out competing another so the number are no longer sufficient to breed
36
Q

Food chains

A
  • Start with producers and producers produce their own food using energy from the sun
  • Producers are green plants/algae, they make glucose
  • Glucose make other biological molecules which are the plant’s biomass - mass of living material
  • Biomass can be though of a energy store in a plant
  • Energy transferred through living organisms in an ecosystem when organism eat other organism
  • Producers eaten by primary consumers, then secondary consumers eat primary consumer and tertiary consumers eat the secondary consumer
37
Q

Population of Prey and Predator cycle

A
  • Stable community contain prey and predators
  • Population of any species is usually limited by the amount of food available
  • When the population of the prey increase, the population of predator rise
  • However when the population of prey decrease the population of predator decrease
  • Predator - prey cycle are out of phase as it takes a while for the population to respond to the changes
38
Q

Carbon Cycle

A
  • CO2 removed from the atmosphere by green plants and algae during photosynthesis, carbon used to make glucose for carbohydrates, fats and proteins that make up the body of the plant and algae
  • When the plants and algae respire, some carbon is returned into the atmosphere as CO2
  • When plants and algae eaten by animals some carbon becomes part of the fats and protein in the body
  • When plants/algae/animals die other animals called detritus feeder and microorganisms feed on their remains.
  • When these organisms respire CO2 is returned to the atmosphere
  • Animals also produce waste that is broken down by detritus feeders and microorganisms
  • Combustion of wood and fossils fuels release CO2
  • Carbon is constantly cycled
39
Q

Water cycle

A
  • Energy from Sun makes water evaporate from the land into water vapour also water that evaporates from plants via transpiration
  • Warm water vapour carried upwards as it rises it cools and condenses to form clouds
  • Water falls from the clouds as precipitation onto land where it provides fresh water for plants and animals
  • It then drains into the sea before the whole process starts again
40
Q

Polluting water

A
  • Minerals such as nitrates used in fertilisers are easily washed from the soul into local streams/ponds/rivers
  • Untreated sewage is washed into waterways or pumped out into the sea, which means high levels of nitrates
  • Nitrate stimulate the growth of algae and water plants
  • Some plants die and other die due to more competition for light
  • Big increase in microorganisms feeding on the dead plants, and they use up of oxygen
  • Increase in decomposers leads to a fall in dissolved oxygen in the water so there is not enough oxygen for aerobic organisms
  • Also toxic chemicals like pesticides/herbicides/ poisonous chemicals from landfills sites can be washed into waterways and bioaccumulation as an affect aquatic foods webs and the build up of these chemicals can kill large carnivores
41
Q

Polluting land

A
  • If human waste is not treated properly, the soil becomes polluted with unpleasant chemicals and gut parasites
  • Toxic chemicals from the waste can spread into the soil
  • Toxic chemicals can poison the soil for miles around
  • Land can also pollute as a side effect farming as weed compete with crop for light/water/mineral ions and animals and fungal pests attack crops and eaten them.
  • So farmers use chemicals to protect their crops as they don’t affect the crop and kill weeds (Weed killers) and pesticides
  • However these can go into the soil and this can lead them to be washed out into streams and rivers and they become part of foods chain when the toxins get into organism
  • It builds up through the food chain as the toxin build up increases (bioaccumulation)
42
Q

Acid rain

Air pollution

A
  • When CO2 is released into the atmosphere the fossil fuels often contain sulfur impurities which react with oxygen and when they are burnt it forms sulfur dioxide
  • This can cause breathing problems if concentration is too high
  • Acidic sulfur dioxide and nitrogen oxide also dissolve in rainwater and react with oxygen in the air to form dilute sulfuric and nitric acid and this produces acid rain
  • Acid rain damages the environment as it can kill leaves/flower/fruits
  • If acid rain falls on water it can cause the water to be acidic and if the concentration gets too high organism cannot survive
43
Q

Smoke pollution

Air pollution

A
  • Increase number of tiny solid particles called particulates int eh air
  • The sulfur products obtain from burning fossils fuels cause the particles to reflect sunlight so less lights the surface of the Earth
  • This causes a dimming effect and this leads to cooling of the temperature at the surface
44
Q

Rate of Decomposition

A
  • Temperature - increase temperature means faster decay as organism work faster in warmer condition. They slow down when it is cold and decay stops when it’s hot as the enzyme denature
  • Moisture - microorganism grow faster in moist condition, it makes it easier for them to digest their food and prevent them from drying out
  • Oxygen - most decomposers respire aerobically so they need oxygen to break down food and transfer energy, grow and reproduce
45
Q

Using Quadrats

A
  • An experiment method to determine the distribution and abundance of species in an ecosystem
    1) Place a quadrat on the ground at a random point with the first sample area (divide the area into a grid and use a random number generator to pick coordination)
    2) Count all the organism within the quadrat
    3) Repeat steps 1 and 2
    4) Work out the mean number of organism per quadrat within the first sample area
    5) Repeat step 1 and 4 with a second sample area
    6) Compare the two means
46
Q

Using Transects

A
  • Use transects to find out how organism are distributed across an area
    1) Mark out a line in the area you want to study using a tape measure
    2) The collect data along the line
    3) Count all the organisms
47
Q

Argument against and for embryonic screening

A

Against Embryonic Screening :
- Implies people with genetic problems are ‘undesirable’ - increase prejudice
- May come a point where everyone wants to screen their embryos so they can pick their most desirable characteristics
- Screening is expensive
For Embryonic Screening :
- It will help stop people from suffering
- Treating disorders cost the Government and people a lot of money
- Laws to stop parents select the sex of their baby

48
Q

Endocrine system

A
  • Is a system composed of glands that secrete chemicals called hormones directly into the bloodstream and the blood carries the hormone to a target organ
49
Q

Pituitary Glands

A
  • Produces many hormones that regulate body condition and it’s called the ‘master gland’
50
Q

Thyroid

A
  • This produces thyroxine which involves the regulating rate of metabolism, heart rate and temperature
51
Q

Adrenal Gland

A
  • Produces adrenaline which is used to prepare the body for a ‘fight or flight’ response
52
Q

Pancreas

A
  • Produces insulin which is used to regulate the blood glucose level
53
Q

Ovaries

A
  • Produce oestrogen which involved in the menstrual cycle
54
Q

Testes

A
  • Testosterone which controls puberty and sperm production in males
55
Q

Hormones vs Nerves

A
  • Nerves : Very fast action, act for a very short time and act very precise area
  • Hormones : Slower action, act for a long time and act in more general way

Biology (2 decks)

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