Untitled spreadsheet - Sheet1 Flashcards
Embryonic screening 3 pros/3 cons
Pros
What is Variation ?
inherited differences in Organisms caused by genetics or environmental factors
How can genes and environmental factors affect variation ?
Genes-differences in the genotype
What are mutations ?
Changes to the sequence of bases in DNA. Mutations include substitutions, deletions and additions.
How do mutations occur?
Randomly. Increased by exposure to certain substances e.g. carcinogens and radiation.
Explain why the function of a protein might be affected by a mutation.
Mutations in the base sequence could affect the amino acid sequence. This will change the shape of the protein. E.g. with enzymes the active site might change shape so that the substrate cannot bind.
Give an example of where genetic variants(mutations) determine phenotype
Cystic fibrosis caused by a mutation that affects phenotype
What is the theory of Evolution?
All of today’s species have evolved from simple life forms that first started to develop over 3 billion years ago
What theory did Charles Darwin come up with?
Evolution by Natural selection
Explain why Darwin’s theory was considered controversial when it was first proposed.
-Against religious beliefs about how life on Earth developed
What 3 things developed/supported Darwin’s Theory of Evolution?
-Discovery of genetics (Mendel/Watson and Crick)
How did the discovery of genetics support Darwin’s theory?
It explained WHY NEW characteristics appeared or how organisms passed on their beneficial adaptations.
Name another scientist who had a theory about evolution.
Jean Baptiste Lamarck
Describe Jean Baptiste Lamarck’s theory.
Theory of Acquired characteristics. E.g. if a giraffe stretched it’s neck to reach tall branches over time the neck would get longer.
Describe speciation.
Speciation-over time, a phenotype of organisms will change so much due to NATURAL SELECTION that a new species is formed.
When does speciation happen?
When POPULATIONS of the SAME SPECIES change enough to become re productively isolated.
What is extinction +4 reasons
No individuals of a species remain
What is selective breeding? + process
Humans artificially select which organisms to breed so that the GENES for particular characteristics remain in the population
Give some examples of selective breeding
Agricultural animals to produce more meat/milk
What is the main issue of selective breeding?
Reduction in the gene pool-the number of different alleles in a population
What is inbreeding? + cons
Where the farmer only breeds from the ‘best’ of animals/plants
What is genetic engineering ?
The transfer of a gene for a desirable characteristic from one organism’s genome into the other’s, so that it also has that desired characteristic.
Process of genetic engineering
1) useful gene cut from one organism’s genome using ENZYMES and inserted into a VECTOR.
Give 3 examples of where genetic engineering has been used
1)GM crops have modified genes to improve SIZE/QUALITY of fruit , and make them RESISTANT to herbicides, pesticides or disease
2 pros & 2 cons of GM crops
ERROR!
How might GM crops help people in the developing world?
People in the developing world often lack nutrients in their diet. GM crops could be engineered to contain the missing nutrient e.g. Golden rice is a GM crop that contains Beta Carotene-lack of this substance causes blindness.
Describe how animals can be cloned by adult cell cloning. [6]
The nucleus is removed from an unfertilised egg.[1] A complete set of adult chromosomes from an adult body cell is inserted into the egg. [1] The egg cell is then stimulated to divide to form an embryo by being given an electric shock.[1] The embryo is then implanted into an adult female [1] where it develops into a clone of the original adult body cell.
Explain the ethical implications around cloning animals.
-Reduced gene pool
Describe how you could clone a plant. (Tissue Culture)
Tissue culture- A few plant cells are put in a growth medium with hormones and they grow into new plants. Plants can be made quickly and cheaply in very little space.
Describe how you could clone a plant. (Cuttings)
Take a cutting from good parent plants. Dip into rooting powder and plant. Can produce plants quickly and cheaply.
What are fossils and give 3 ways they form in rock
THE REMAINS OF PLANTS AND ANIMALS FORMED IN ROCK
Explain Antibiotic Resistance
Bacteria DNA RANDOMLY MUTATES. Taking antibiotics creates a selective pressure as the environment changes. Selects the resistant strain as better adapted. This can lead to antibiotic resistant strains. More likely to survive and reproduce. Gene for antibiotic resistance increases in the population.
Give 3 reasons for antibiotic resistance
1-not taking the full course of the treatment-leaving some bacteria unkilled-ready to mutate
What is classification?
Organising living organisms into groups/kingdoms which are then divided into smaller groups of different structures/characteristics
Explain the Carl Woese three-domain system
- Archaea-PRIMITIVE BACTIERIA often found in EXTREME PLACES such as hot springs/salt lakes
What is the binomial system?
Organisms are named according to this system.
What do Evolutionary trees show?
EVOLUTIONARY RELATIONSHIPS eg ancestry
Competition
The process by which living organisms compete with each other for limited resources
What do organisms require to survive and reproduce?
A supply of materials from their surroundings and other living organisms
What do plants compete with each other for? (4)
Light, space, water, and mineral ions
What do animals compete with each other for? (3)
Food, mates and territory
Stable community
Where all the species and environmental factors are in balance so that population sizes remain fairly constant
What happens if one species is removed from a community?
It can affect the whole community
Abiotic factors
Non-living factors
Biotic
Living factors
Name 7 abiotic factors and how they might affect a community
- Light intensity - photosynthesis, breeding cycles linked to day length
Name 4 biotic factors and how they might affect a community
- Availability of food - food allows animals to survive and breed successfully
Adaptations
Features which enable an organism to survive in the conditions in which they normally live
Adaptations may be…
…structural, functional or behavioural
Examples of structural adaptations
Features of body structure, shape or colour - e.g. animals living in cold environments have small ears (low SA:vol ratio), Arctic foxes have white fur, whales have blubber, herbivores have teeth for grinding up plant cells
Examples of behavioural adaptations
Basking, migration, tool use - e.g. birds migrate, nocturnal to avoid heat of day
Examples of functional adaptations
Processes inside body - e.g. reduced sweating, animals in extreme winter temperatures produce a chemical in cells which cacts as an antifreeze
Extremophiles
Organisms that live in very extreme environments, such as high temperature, pressure or salt concentration
Eaxmple of extremophiles
bacteria living in deep sea vents (at very high pressure, no light, acid pH)
Photosynthetic organisms are…
.the producers of biomass for life on earth
How can feeding relationships within a community be represented?
With food chains
Describe the structure of food chains, giving examples. (3)
- All food chains begin with a producer which synthesises molecules e.g. green plants, algae, which make glucose by photosynthesis
Predators
Consumers that eat and kill other animals
Prey
Animals eaten by predators
In a stable community, the numbers of predators and prey…
…rise and fall in cycles
What are 2 methods used by ecologists to determine the distribution and abundance of species in a ecosystem?
Transects and quadrats
Quadrat
A square made of wire used to estimate population size of plants or slow moving animals. It may have smaller squares of wire within it.
How do you use a quadrat?
- Choose a sample area at random. Use random number tables and coordinates
How can we ensure this quadrat investigation is a fair test?
- Sample as many areas as possible to increase sample size and make the results more valid
What is an issue with quadrat investigations?
Time consuming and difficult if animals are present
Sampling is also used to…
…measure changes in the distribution of organisms over time. Repeat measurements at regular time intervals and calculate mean. Finding the range of distribution and the median and mode of your data can also be useful.
What factors could you investigate in an experiment about the distribution of species? (3)
- Trampled/untrampled grass
Quantitative sampling
Records the number of organisms rather than just the type
Mean
Sum of values divided by number of values
Median
The middle value of the range
Mode
The most frequently occuring value
How does a line transect work?
- Stretch a tape between 2 points.
Why are all materials in the living world recycled?
To provide the building blocks for future organisms
The carbon cycle
Returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis
The water cycle
Provides fresh water for plants and animals on land before draining into the seas. Water is continuously evaporating and precipitating.
Why is the carbon cycle important?
Carbon is an important element which makes up many different molecules in our environment and bodies (carbohydrates, fats and proteins). The amount of carbon on the Earth is fixed so it must be recycled.
Describe the water cycle
- Evaporation: water evaporates from the surface of land and bodies of water
Why is the water cycle important?
Water is vital for life. The water cycle provides fresh water for plants and animals to survive.
The role of microorganisms in cycling
Decay by microorganisms returns carbon dioxide to the atmosphere by respiration and mineral ions to the soil.
Detritivores
Detritivores/detritus feeders e.g. maggots and flies feed on dead, rotting material. They break up the dead organism into smaller pieces, increasing the surface area for digestion by microorganisms.
Describe the nutrient cycle (decay) (6)
- Decay starts after death of organism
How does temperature affect the rate of decay?
- High temperatures denature enzymes and other proteins, killing the organisms responsible for decay
How does water affect the rate of decay?
Lack of water slows or prevents decay - water needed for decay organisms to digest their food and to support reactions inside organisms
How does availability of oxygen affect rate of decay?
Lack of oxygen slows or prevents most types of decay - needed for anaerobic respiration, but some anaerobic bacteria can survive without e.g. in biogas generators
How is rate calculated?
1/time or 1000/time
What to farmers and gardeners do to achieve rapid decay of waste biological material?
Provide optimum conditions
What is the compost produced from this decay used for?
A natural fertiliser for growing plants or crops
What does anaerobic decay produce?
Methane gas
How do biogas generators work?
Anaerobic decay of biomass produces methane gas as a fuel
Describe an experiment to investigate the effect of temperature on the rate of decay of fresh milk using pH.
- Full fat milk, phenolphthalein indicator, and alkaline solution (eg sodium carbonate) in several tubes - this will be pink
Environmental changes affect…
…the distribution of species in an ecosystem
What do environmental changes include? (3)
- Temperature
These environmental changes may be…
…seasonal, geographic or cuased by human interaction
Geographical changes
Includes many different factors including difference in soil structure or pH, altitude, saltiness of water
Seasonal changes
- In temperate areas, the temperature rainfall, daylight and other factors change dramatically between seasons, as does the distribution of plants and animals
Changes as a result of human interaction
- Global warming and climate change - nwo working to maintain rainforest
Biodiversity
The variety of all the different species of organisms on earth, or within an ecosystem
What does a greater biodiversity ensure?
Ensures the stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment
What does the future of the human species on Earth rely on and why?
- Relies on us maintaining good levels of biodiversity
How do humans reduce biodiversity? (4)
- Waste management
More pollution will be caused, unless…
…waste and chemical materials and properly handled
Why is more waste being produced?
- Rapid growth in human population
Where can pollution occur and from what?
- Water - sewage, fertiliser, toxic chemicals
What effect does pollution have on biodiversity?
Pollution kills plants and animals which can reduce biodiversity
How do humans affect biodiversity through land use? (2)
- Humans reduce the amount of land available for other animals and plants
Why is the destruction of peat bogs a problem?
- Peat bogs and other areas of peat are destroyed to produce garden compost
Why has large-scale deforestation occurred in tropical areas? (2)
- To provide land for cattle and rice fields and palm oil.
What factors are conflicting in the destruction of beat bogs?
- The need for cheap available compost to increase food production
Describe global warming
- CO2 and methane contribute to the greenhouse effect - they absorb some of the Sun’s energy which is reflected off the earth
Describe some of the biological consequences of global warming (4)
- Loss of habitats - due to rising sea levels
What is the scientific consensus about global warming and climate change based on?
Systematic reviews of thousands of peer reviewed publications
Describe programmes put in place to reduce the negative effects of humans on ecosystems and biodiversity
- Breeding programmes for endangered species
Describe the 4 trophic levels
Level 1. Producers - plants and algae make their own food
Apex predators
Carnivores with no predators
What is the role of decomposers?
Break down dead plant and animal matter by secreting enzymes into the environment. Small soluble food molecules then diffuse into the microorganisms.
Pyramids of biomass
Trophic level 1 is always at the bottom of pyramids of biomass. The pattern moving up through the trophic levels will always be the same. Remember to label each bar.
Why is the biomass in each trophic level less than the previous level
- Not all parts of the organism are eaten e.g. bones left behind
Producers are…
…mostly plants and algae which transfer about 1% of the incident energy from light for photosynthesis
Only around … of the biomass from each trophic level is transferred to the level above it
10%
How do you calculate efficiency of biomass transfer between trophic levels?
efficiency = biomass transferred to next level/biomass available at previous level x 100
How do the levels of biomass affect the number of organisms at each trophic level?
Normally as you move up trophic levels and the biomass decreases, the number of organisms also decreases
Food security
Having enough food to feed a population
Biological factors which are threatening food security
- Increasing birth rate - in some countries
Example of a pathogen affecting food security
Blue tongue’ disease carried by midges spreading to sheep and cattle in the UK from Europe
… methods must be found to feed all people on Earth
Sustainable
How can the efficiency of food production be improved?
By restricting energy transfer from food animals to the environment
How can energy transfer from food animals to the environment be restricted? (2)
- Limiting their movement
How is the growth of some animals increases?
They are fed high protein foods
Ethical objections to modern intensive farming methods
- Intensively farmed animals suffer in uncomfortable conditions
What is happening to fish stocks in the ocean?
They are declining
Why is it important to maintain fish stocks at a level where breeding continues?
Otherwise certain species may disappear altogether ins ome areas
Methods for conserving fish stocks at a sustainable level
- Control of net size - larger nets mean small, young fish can escape and continue to breed
Modern biotechnology techniques enable…
…large quantities of microorganisms to be cultured for food
A protein-rich food suitable for vegetarians
Mycoproten
How is mycoprotein produced?
- The fungus Fusarium is grown on glucose syrup in aerobic conditions
How can we use a genetically modified bacterium to treat people with diabetes?
A genetically modified bacterium produces human insulin which can be harvested, purified and used to treat people
How GM crops could be used?
To provide more food or food with improved nutritional value such as golden rice
