Natural selection and GM Flashcards
SB4a Evidence for human evolution
A) Describe the features of Ardi & Lucy
B) How does this provide evidence for evolution?
( Include Richard Leakey’s discovery )
1. Ardi
- Her leg bones show she may have been able to walk.
- She had very big arms.
- Very big toes that would have allowed her to climb trees.
- 4.4million years old.
2. Lucy
- She could probably walk upright
- However, her toe bones were arranged in the same way of that of modern humans.
- 3.2million years old
B) The skeleton of Lucy is more recent & has more similarties to modern humans than that of Ardi which suggests that evolution is occuring.
- Also, the Richard Leakey discovered a 1.6million year old fossil that looks more like modern humans than Lucy or Ardi, further proving this point.
SB4a Evidence for human evolution
Describe how;
A) Stone tools can be dated from their enviroment.
B) These tools provide evidence for evolution
A) Tools can be dated from the environments they were found in.
- Dating can be done by radiocarbon dating or other techniques which look at the amounts of elements.
B) Tools found in the oldest rock tended to be very simple ( used for skinning animals or cutting up meat ). While tools found in more recent rock tended to be more sophisticated.
SB4b Darwin’s theory
What did Charles Darwin propose with his Theory of evolution?
1. Individual organisms within a particular species show a wide range of variation for a characteristic.
2. Individuals with characteristics most suited to the environment are more likely to survive and to breed successfully.
3. The characteristics that have enabled these individuals to survive are then passed on to the next generation.
This is Natural Selection
SB4b Darwin’s Theory
What was the name of the other scientist involved in the theory of Natural Selection & how did his works encourage Charles Darwin?
1. Alfred Russel Wallace was a fellow naturalist who gathered evidence for his evolutionary theory, best known for studying warning colouration in animals.
- E.g. ~ Golden Birdwing Butterfly
2. After a variety of zoological discoveries Wallace proposed a theory of evolution, which matched Darwin’s unpublished ideas. Encouraging Darwin to publish on;
- On the Origin of Species
SB4b Darwin’s Theory
What evidence did Darwin use to support his theory?
- In 1835, Darwin visited the Galapogos where he noticed differences between finches & mockingbirds on different islands.
- He wondered if a species could change form if it moved to a different area.
SB4b Development of Darwin’s theory
How did Charles Darwin’s theory affect ideas surrounding evolution.
- Biologists started to think about how and why organisms changed ( rather than just observing them ), and especially how variation occured.
- This led to the development of modern ‘molecular biology’ and genetics.
SB4c Development of Darwin’s theory
What is a pentadactyl limb & how does this provide support to Charles Darwin’s theory?
1. All vertebrates have limbs with 5 fingers, these are known as pentadactyl limbs.
2. These provide support for Darwin’s theory of evolution as the limb bone structure suggests evolution from a common ancestor.
- Through Natural Selection, to suit our enviroment, each species’s pentadactyl limb evolved indepentatly for it’s specific purpose.
SB4d Classification
How did Carl Linnaeus ( 1735 ) classify organisms?
1. Carl Linnaeus divided organisms purely fbased of of what they looked like.
2. His largest group ( Kingdoms ) were plant and animals, which were divided into even smaller groups.
3. Linnaeus used the last 2 groups ( genus & species ) to give each organism it’s binomial name.
- The genus comes before the species.
4. Linnaeus’s method was fault as organisms may have evolved similar characteristics but not be closely related.
SB4d Classification
What are the 5 Kingdoms?
( Include Characterstics of Each )
1. Animals
- Multicellular
- Cells have nuclei
- No cell walls
2. Plants
- Multicellular
- Have chloroplasts for photosynthesis
- Cells have nuclei
- Cellulose cell walls
3. Fungi
- Multicellular ( Apart from yeasts )
- Live in/on the dead matter on which they feed.
- Cells have nuclei.
- Cell walls contain chitin ( Not Cellulose )
4. Protists
- Mostly unicellular
- Cells have nuclei
- Some have cell walls ( Not Made of Chitin )
5. Prokaryotes
- Unicellular
- Cells do not have nuclei
- Flexible cell walls
SB4d Classification
What are the 3 Domains
1. Archaea - Cells with no nucleus, genes contain unused sections of DNA
2. Bacteria - Cells with no nucleus, no unused sections of DNA
3. Eukarya - Cells with a nucleus, unused sections of DNA
- This is where most the 5 Kingdoms classify
SB4d Classification
Explain why biologists now classify
organisms into 3 domains.
1. This system is heavily based on the evidence provided by genetic analysis.
- Genetic analysis - The study of a sample of DNA
2. This genetic analysis showed that all organisms apart from prokayotes have unused section of DNA.
3. Most of a gene is used to make protien, but these ‘unused’ section did not help.
- Archaea was also found to have these ‘unused’ sections.
4. This lead to Carl Woese proposing that organisms should be split into 3 Domains.
SB4e Breeds and varieties
List some things plants & animals are often selectively bred for.
1. Disease Resistance ( how well they cope with disease )
2. Yield ( how much useful product they make )
3. Coping with certian enviromental conditions
4. Fast growth
5. Flavour
SB4e Breeds and varieties
A) Describe the process of Selective Breeding.
B) Provide the Advantages & Disadvantages of it
A) Selective Breeding Method
1. Select a male and female of the species with the desired characteristics.
2. Breed them together
3. Select the offspring with the desirable characteristic and breed them.
4. Repeat over many generations.
B) Advantages & Disadvantages
1. Advantages
- Higher chance for desired characteristics
- Can be selected for advantageous traits
2. Disadvantages
- Less genetic variaiton
- Takes a long time
- Animal Welfare is a concern.
- Allelles that may be useful in the future dissapear.
SB4e Breeds and varieties
Describe what is ment by a Genetically Modified Organisms ( GMO )
This is when the DNA of an organism is changed by inserting the genes from another organisms.
SB4f Tissue Culture
Describe what is mean by Tissue Culture.
1. Tissue Culture is the growing of cells or tissues in a liquid containing nutrients or on a solid medium ( such as nutrient agar )
- This is a useful way to grow many identical cells.
2. These may form a callus ( a group of undifferentiated cells ). Sometimes the cells are are then treated to make them differentiated
SB4f Tissue Culture
Describe the Uses/Advantages of Tissue Culture in;
A) Medicine
B) Plants
A) Medicine
1. Culturing a thin layer of cells on a solid medium makes it easier to study how cells interact with eachother.
2. Cell cultures are needed to study viruses, which cannot be replicate outside of cells.
- Allowing Scientists to see how viruses spread.
3. Scientists can study cell cultures without risking harm to animals or humans.
B) Plants
1. Allows scientists to produce new plants of very rare species on the brink of extinction.
2. Also used to produce new individuals of plant species that may be difficult to grow from seeds.
- E.g. - Orchids
SB4f Tissue Culture
Describe the process of plant cloning via Tissue Culture.
1. A piece of plant is placed in bleach solution to sterilse it.
2A. Sometimes, a small piece of of plant is cut off and placed on sterile nutrient medium to grow.
2B. Sometimes, only a few cells are cut off, and placed on on sterile nutrient medium to grow into a callus.
3. The callus/piece of plant is treated with hormones so that plantlets develop with shoots and roots.
4. The plantlets are separated and grown on nutrient mediums in sterile conditions.
5. When the plants are large enough, they are planted into soil or compost.
SB4g Genes in agriculture and medicine
Describe the process to Genetic Engineer Insulin.
1. Identify the desired gene in the vector before using restriction enzymes to make staggered cuts in DNA molecule, producing sticky ends.
- DNA containing insulin gene is cut this way.
2. Using the same restriction enzyme, cut the plasmids open creating complentary sticky ends.
3. The DNA and plasmids are now joined together using an enzyme called ligase.
4. The plasmids are then inserted back into the bacteria to allow it to develop with the insulin gene.
SB4h GM and agriculture
Describe the Advantages & Disadvantages of Genetic Engineering
A) Advantages
1. GE is a faster and more efficient way of getting the same results as selective breeding.
2. Improves crop yields or crop quality, which is important in developing countries.
3. Insect resistance from Bacillus thuringiensis can be inserted into the plants.
- The plant produces toxins, which would discourage insects from eating the crop.
4. Introduce herbicide resistance, which results in less herbicides being used, as weeds are quickly and selectively killed.
B) Disadvantages
1. Some people believe it is not ethical to interfere with nature in this way.
2. Genetically engineered crop seeds are often more expensive.
3. Genetically engineered crops could be harmful.
- For example toxins from the crops have been detected in some people’s blood
4. Genetically engineered crops could cause allergic reactions in people.
Bacillus thuringiensis - A bacterium capable of producing a natural toxin called Bt toxin.
SB4i Fertilisers and biological control
A) What are Biological Controls?
B) Provide Advantages & Disadvantages of using them.
Biological Control - using predator oraganisms to kill problem oragnisms, such as weeds or pests.
A) Advantages
1. They can be specific to a particular pest
2. Using organisms means it will be a self-sustaining system
3. It is cheap to maintain.
B) Disadvantages
1. Can sometimes fail in it’s specifity
- Control organisms may eat unintended crops or animals
2. It’s a rather slow process
3. The start-up process can be expensive.
4. It won’t completely destory a pest.
SB4i Fertilisers and biological control
Describe how Fertilisers are used.
1. Fertilisers contain mineral ions, such as nitrogen, potassium and phosphorus.
2. The plants absorb these minerals from the soil to make healthy new cells.
SB4i Fertilisers and biological control
Describe the Advantages & Disadvantages of using Fertilisers.
A) Advantages
1. Using Fertilisers helps us to icnrease the growth and yield of crop plants.
B) Disadvantages
1. If not all the fertiliser is absorbed by the crops, it could get into nearby streams, rivers and lakes.
- This can lead to pollution and the death of organisms in the water.
2. It can also harm humans and animals who drink from the water.
