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)