B4 - Natural Selection and Genetic Modification Flashcards
Define
evolution.
the slow and continuous change of organisms from one generation to the next
Describe the process of
natural selection.
(6 steps)
- Individuals in a population have genetic variation due to difference in their alleles.
- Competition for resources, predation and disease affect an organism’s chance of surviving and reproducing.
- Those individuals with characteristics that make them better adapted to their environment have a better chance of survival, so are more likely to breed successfully.
- The alleles that are responsible for the useful characteristics are more likely to be passed on to the next generation.
- Some individuals will be less well adapted to the environment and will be less able to compete. So, are less likely to survive and reproduce.
- The beneficial characteristics become more common in the population over time.
Define
fossil.
a trace of an animal or plant that lived a long time ago
(over a thousand years ago)
What are two
evidences for evolution?
(2)
- antibiotic resistance of bacteria
- fossils
What did
Charles Darwin do?
(4 steps)
- Spent 5 years on a voyage aroudn the world studying plants and animals on a ship called the HMS Beagle.
- Noticed that there was variation in members of the same species and that those with characteristics most suited to the environment were more likely to survive.
- Noticed that the characteristics could be passed on to offspring.
- Wrote the book ‘On the Origin of Species’ explaining his observations
What did
Alfred Wallace do?
(2 things)
- Came up with the idea of natural selection independently of Darwin.
- Observed lots that helped evidence the theory of evolution by natural selection.
In what areas have
ideas about evolution influenced modern biology?
(3)
- classification - organisms are classified by how closely related they are
- antibiotic resistance - the course of drugs must be finished to prevent resistant bacteria spreading, new antibiotics must be constantly developed to fight newly evolved resistant bacteria
- conservation - gentic diversity is very important as it helps populations adapt to changing environments
What are
hominids?
human beings and their ancestors
Tell me about
Ardi.
- full name?
- age?
- location?
- Ardipithecus ramidus
- 4.4 million years old
- Ethiopia
What are some
characteristics of Ardi?
(4)
- Feet structured to climb trees - ape-like big toe.
- Long arms, short legs
- Small brain size
- Walked upright - deduced by leg structure and hand bone structure
Tell me about
Lucy.
- full name?
- age?
- location?
- Australopithecus afarensis
- 3.2 million years old
- Ethiopia
What are some characteristics of
Lucy?
(4)
- Arched feet and no ape-like big toe - more adapted to walking than climbing.
- Shorter arms and legs (than Ardi).
- Slightly larger brain (than Ardi).
- Walked upright, more efficiently (than Ardi) - deduced by leg and feet bone structure.
Tell me about
Turkana boy.
- discovered by?
- location?
- age?
- species name?
- discovred by Richard Leakey
- Kenya
- 1.6 million years old
- Homo erectus
What are some characteristics of
Turkana boy?
(4)
- has a mixture of human and ape-like features (more human-like than Lucy)
- has short arms and long legs
- much larger brain size (than Lucy)
- even better adapted to walking upright (than Lucy)
What are some ways in which
scientists can work out how old a fossil or stone tool is?
(3)
- Look at the structual features of the tool or fossil.
- Study the rock layers.
- Use carbon-14 dating to date materials used in stone tools.
What is a
pentadactyl limb?
a limb with five digits
How does the
pentadactyl provide evidence for evolution?
the similarity in bone structure of pentadactyle limbs provides evidence that the species have all evolved form a common ancestor (that had a pentadactyl limb)
if they’d all evolved from different ancestors, then it’d be highly unlikely that they’d share a similar bone structure
How were organisms classified in the
five kingdom classification system?
according to similarities and differences in organisms observable characteristics
What are the
five kingdoms?
(of the five kingdom classification system) (+ examples)
- Animals - fish, mammals, reptiles
- Plants - grass, trees
- Fungi - mushrooms, yeast
- Prokaryotes - single-celled organisms without a nucleus
- Protists - eukaryotic single-celled organisms, algae
Why have
classification systems changed over time?
Over time, technology has developed further and our understanding of things like biochemical processes and genetics has increased.
Organisms are now classified using RNA sequencing.
What are the
three domains?
(of the three domain classification system)
- Archaea
- Bacteria
- Eukarya - e.g. fungi, animals, plants, protists
Define
selective breeding.
the process of humans artificially selecting the plants or animals that are going to breed so that genes for particular characteristics remain in the population
What are some examples of
selectively bred organisms?
- animals that produce more meat or milk
- crops with disease resistance
- dogs with good, gentle temperament
- plants that produce bigger fruit
How has selective breeding been used in
medical research?
When investigating alcoholism, rats have been bred with either a strong or weak preference for alcohol. This has allowed researchers to compare the differences between the two different types of rats.
This includes differences in their behaviour and in the way that their brains work.
What is the main
disadvantage of selective breeding?
and why is this so bad?
Inbreeding - selective breeding reduces the gene pool, resulting in closely related animals or plants being bred.
This can cause health problems because there’s more chance of organisms inheriting harmful genetic defects.
This can also be a serious problem if a new disease appears. There’s not much variation in the population, so there’s less chance of resistant alleles being present. So, if one stock is killed by a new disease, the others are also likely to succumb to it.
What does
tissue culture involve?
growing cells on an artifical growth medium
What are the advantages of
tissue culture?
(5)
- easy
- very quick
- takes little space
- can be grown all year
- can create clones with the same beneficial features
Describe the process of
tissue culture.
(of plants) (4 steps)
- Choose the plant you wish to clone based on its characteristics.
- Remove several small pieces of tissue from the parent plant.
- Grow the tissue in a growth medium containg nutrients and growth hormones.
- As the tissues produce roots and shoots they can be moved to potting compost to carry on growing.
Why should tissue culture be made in
aseptic conditions?
in order to prevent the growth of microbes that could harm the plants
Why is
animal tissue culture often used in medical research?
Experiments can be carried out on tissues in isolation in order to look at the effects of a particular substance or environmental change on the cells of a single tissue, without complications from other processes in the whole organism.
Describe the process of
tissue culture of animal cells.
(4 steps)
- Extract a sample of the tissue you want to study from the animal.
- Separate each of the cells using enzymes.
- Place the cells in a culture vessel and bathe them in a growth medium containing all the nutrients necessary.
- After several round of cell division, split the cells up again and place them into separate vessels to encourage further growth.
Once the tissue culture has been grown, it can be stored for future use.
What does
genetic engineering involve?
modifying an organism’s genome to introduce desirable characteristics
Define
recombinant DNA.
two different bits of DNA that have been stuck together
What do
restriction enzymes do?
recognise specific sequences of DNA and cut the DNA at these points
the pieces of DNA are left with sticky ends where they have been cut
What does
ligase (enzyme) do?
join two pieces of DNA together at their sticky ends
What is a
vector?
something that is used to transfer DNA into a cell
What are the
two types of vector?
- plasmids
- viruses
Describe the process of
genetic engineering.
(6 steps)
- Cut out the DNA you want to insert using a restriction enzyme.
- Cut the vector DNA using the same restriction enzyme.
- Mix the vector DNA and insert DNA with ligase enzymes.
- The ligases join the pieces of DNA together to make recombinant DNA.
- This DNA is inserted into other cells.
- These cells can now use the gene you inserted to make the protein you want.
What are some uses of
genetic engineering?
(3 things)
- crops can be modified to be resistant to herbicides
- human genes that produce useful proteins can be transferred to sheep and cows - so that the proteins can then be extracted from the animal
- human insulin producing bacteria
What are some
concerns surrounding genetic engineering and its products?
(3)
- it can be hard to predict what effect modifying an animal’s genome will have on the organism
- transplanted genes (in plants) may get out into the environment
- genetically modified crops could adversely affect food chains or even human health
Describe how
insect resistant plants can be made.
(2)
- Bacillus thuringiensis produces a toxin that kills many of the insect larvae that are harmful to crops.
- The gene for Bt is then inserted into crops which then produce the toxin from their stems and leaves - making them resistant to the insect pests.
Define
food security.
the global access to enough food that is safe to eat and has the right balance of nutrition
What are some concerns surrounding
genetically modified crops being used to provide more food for people?
(3)
- many people go hungry because they cannot afford to buy food, rather than the lack of food
- countries may become dependent on companies who sell GM seeds
- sometimes it is poor soil that is the main reason why crops fail, so even GM crops won’t survive
