Topic 6- Inheritance, variation & evolution: Flashcards
1
Q
Charles Darwin:
A
- Scientist
- Put forward the theory of evolution
- Supported by experimentation and his knowledge of geology and fossils
2
Q
Theory of evolution:
A
- Variation exists within species as a result of mutations in DNA
- Organisms most suited to the enviroment are more likely to survive and reproduce- SURVIVAL OF THE FITTEST.
3
Q
What is variation?
A
Differences in characteristics of a population.
4
Q
What are the causes of variation within a species?
A
- Genetics
- Enviroment
- A mixture of the both
5
Q
What is genetic variation?
A
- Variation in the genotypes of organisms of the same species due to the presence of different alleles
- Creates difference in phenotypes
6
Q
What creates genetic variation in species?
A
- Spontaneous mutations
- Sexual reproduction
7
Q
What is a mutation?
A
A random change to the base sequence in DNA which results in genetic variants. They occuur continouosly.
8
Q
State the three types of gene mutation.
A
- Insertion
- Desertion
- Substitution
9
Q
How may a gene mutation affect an organism’s phenotype?
A
- Neutral mutation- does not change the sequence of amino acids. Protein structure and function same. No effect on phenotype.
- Mutation may cause a change in an organism’s phenotype- e.g. change in eye colour
- Mutation may completely change the sequence of amino acids. This may result in a non-functional protein. Severe changes to phenotype.
10
Q
What is the consequence of a new phenotype caused by a mutation being suited to an enviromental change?
A
There will be a RAPID change n the species.
11
Q
What is evolution?
A
- A gradual change in the inherited traits within a population over time.
- Occuurs due to natural selection which may result in the formation of a new species.
12
Q
Outline the theory of natural selection.
A
All species of living things have evolved from simple life forms that first developed more than 3 billion years ago.
- Genetic variation exists due to spontaneous mutation
- Selection pressures (e.g. competition, disease) exist
- Random mutation give an organism selective advantage
- Organism is better adapted to the enviroment and it survives
- Organism reproduces, passing on it’s beneficial alleles
- Frequency of advantgaeous alleles increases.
13
Q
How do two populations become different species?
A
When their phenotypes become different to the extent that they can no longer interbreed to produce fertile ffspring.
14
Q
What is selective breeding?
A
The process by which humans artificially select organisms with **desireable characteristics **and breed them to produce offspring with similar phenotypes.
15
Q
Outline the main steps involved in selective breeding?
A
- Identify a desired characteristics e.g. disease resistance.
- Selct parent organisms that show that desired traits and breed them together.
- Select offspring with desired traits and breed them together.
- Process is repetated until all offspring have the desired traits.
16
Q
Give examples of characteristics selected for in selective breeding.
A
- Disease resistance in crops
- Higher milk or meat production in animals
- Gentle nature in domestic dogs
- Large flowers
17
Q
What is the main advantage of selective breeding?
A
Creates organisms with desireable features:
* Crops produce a higher yield of grain
* Cows produce greater supply of milk
* Plants produce larger fruit
* Domesticated animals
18
Q
Other than agriculture, where is selective breeding useful?
A
- In medical research
- In sports, e.g. horse racing
19
Q
Outline the disadvantages of selective breeding. (4)
A
- Reduction in the gene pool (which becomes especially harmful if sudden enviromental change occurs.)
- Inbreeding results in genteic disorders
- Development in other physical problems e.g. respiartory problems in bulldogs
- Potential to unkowingly select harmful recessive alleles.
20
Q
What is genetic engineering?
A
- The modification of the genome of an organism by the insertion of a desired gene from another organism- genes from chromosmes of humans and other organisms can be ‘cut out’ and transferred to cells of other organisms.
- Enables the formation of an organism with beneficial characteristics.
21
Q
Give an example of uses for genetically modified plants.
A
- Disease resistant
- Produce larger fruits
22
Q
What is a use for gm bacteria cells?
A
To produce human insulin to treat diabetes mellitus.
23
Q
Describe the benefits of genetic engeneering. (3)
A
- Increased crop yields for growing population e.g. disease resistant
- Useful in medicine e.g. insulin-producing bacteria, posibility to overcome some inheritted disrders
- GM crops produce scare resources e.g. vitamin A from golden rice
24
Q
Describe the risks of genetic enegineering. (4)
A
- Long term effects of GM crops are unknown
- Negative enviromental impacts- reduction in biodiversity, impact on food chain
- Late onset health problems in GM animals.
- GM seeds are expensive
25
What is the **name** for **crops** that have had their **genes modified?**
**Genetically modified crops** e.g. those **modified** to **insect attack** and **herbicides.**
26
What is ***Bacillus thuringiensis*** (Bt)?
* **Insect larvae** are **harmful** to crops.
* Bt is a **bacterium** which **secretes** a **toxin** that **kills insect larvae.**
27
**How** is **genetic engineering** used to **protect crops** against **insects?**
* The **gene** for **toxin production** in **Bt** can be **isolated** and **inserted** into the **DNA of crops.**
* **Bt crops** now **secrete** the **toxin** which **kills** any **insect larvae** that **feed on it.**
28
What are the **benefits** of **Bt crops?**
* **Increased crop yields**
* **Lessens** the need for **artificial insecticides**
* **Bt toxin** is **specific** to **certain** insect larvae so is **not harmful** to **other organisms that ingest it.**
29
What are the **risks** of **Bt crops? (3)**
* **Long term effects** of **consumption** of **Bt crops** are **unkown**
* **Insect larvae** may become **resistant** to the **Bt toxin**
* **Killing** insect **larvae** **reduces biodiversity.**
30
Describe the **process** of **genetic engeneering.**
1. **Enzymes** are used to **isolate** the **required gene;** the gene is inserted into a **vector,** usually a **bacterial plasmid** or a **virus**
2. The **vector** is used to **insert gene** into the **required cells.**
3. **Genes** are **transferred** to the **cells** of animals, plants or microorganisms at aan **early stage** in their **development** so that they **develop** with **desired characteristics.**
31
What is a **vector?**
A **structure** that **delivers** the **desired gene** into the **cell.**
32
**How** can plants be **cloned.** (2)
* Taking plant cuttings
* Tissue culture
33
What is **tissue culture?**
Using **small groups of cells** from **part** of a **plant** to grow **identical** new plants.
34
**Describe** how **plants** are **grown** using **tissue culture.**
1. **Select** a **plant** that shows **desired characteristics.**
2. **Cut** multiple **small sample pieces** fro **meristem** tissue.
3. **Grow** in a **petri dish** containing **growth medium.**
4. Transfer to **compost** for further grow.
35
What must be **ensured** when **preparing tissue cultures?**
Ensure **aseptic conditions** to **prevent contamination** by microorganisms.
36
What does the **growth medium contain?**
Nutrients and growth hormones.
37
What are **advantages** of **growing plants** by **tissue culture?**
* **Fast** and **simple** process
* Requires **little space**
* **Enables** the **growth** of **many plant clones** with the **same** desireable characteristics.
* **Useful** in the **preservation** of **endagered sspecies.**
38
What are the **disadvantages** of **growing plants** by **tissue culture? (2)**
* **Reduction** in the **gene pool**
* **Plant clones** often have a **low survival rate**
* Could **unkowingly increase** the **presence** of **harmful recessive alleles.**
39
**Describe** the **plant cuttings method** of plant cloning.
* **Older** but **simpler** method than **tissue culture**
* **Gardeners** use this method to **produce many identical new plants** from a **parent plant.**
40
**Detail** the process of **plant cuttings** method of plant cloning.
1. A **branch** is **cut off** from the **parent plant.**
2. The **lower leaves** of the **branch** are **removed** and the **stem is planted.**
3. **Plant hormones** are **used** to encourage **new root development .**
4. A **plastic bag** is used to **cover** the **new plant** to keep it **warm** and **moist.**
5. **New roots** and a **new plant** is formed after a **few weeks.**
41
What does **embryo transplanting** **invole?**
* **Pre-specialised cells** from a **developing animal embryo** are **split** apart.
* The resulting **seperate** but **identical embryos** are **transplanted** into **host mothers.**
42
**Decribe** how **adult cell cloning** is performed.
1. The **nucleus** is **removed** from an **unfertilised egg cell.**
2. The **nucleus** from an **adult body cell,** such as a **skin cell,** is **inserted** into the **egg cell.**
3. An **electric shock stimulates** the **nucleated egg cell** to **divide** and it forms an **embryo.**
4. The **embryo cells** contain the **same genetic information** as the **adult body cell.**
5. When the embryo is a **ball of cells**, it's **inserted** into the **uterus** of an **adult female** to **continue developing.**
43
What are the **classes** of **organisms** as determined by **Carl Linnaeus?**
* **Kingdom** (King)
* **Phylum** (Phillip)
* **Class** (Came)
* **Order** (Over)
* **Family** (For)
* **Genus** (Good)
* **Species** (Spaghetti)
44
Which **features** are living **creatures** **traditionally** classified by?
* Structure
* Characteristics
45
What is the **binomial system** of **naming organisms.**
**Genus** follwed by **species** name.
46
**Why** were **new classification models** proposed?
* **Developments in microscopy-** allowed **better** examination of **internal structures.**
* **Improvement** in understanding of **biochemical processes.**
47
State three **domains.**
* Archaea
* Eukarya
* Bacteria
48
Which **organism** lives in the **domain archaea?**
**Bacteria-** living in **extreme** environments.
49
Which **organism** belongs to the **domain Bacteria?**
Bacteria
50
Which **kingdoms** belong in **domain Eukarya?**
* Plants
* Animals
* Fungi
* Protists
51
**How** are **evolutionary trees** created?
By **examining** the **DNA** of **different species** and **analysing** how **similar** the **sequences** are.
