B4 Natural Selection and Genetic Modification

Question 1

Define

evolution.

Answer 1

the gradual change in the characteristics of a species over time

Question 2

What is a

cladogram?

Answer 2

a tree diagram showing the evolutionary relationships and common ancestors

Question 3

What are

nodes?

(on cladograms)

Answer 3

branching points which indicate a speciation event when a common ancestor splits into two or more species

Question 4

When was ‘Lucy’ alive?

Answer 4

3.2 million years ago

Question 5

When was ‘Ardi’ alive?

Answer 5

4.4 million years ago

Question 6

What is the genus and species of

‘Lucy’?

Answer 6

Australopithecus afarensis

Question 7

What is the genus and species of

‘Ardi’?

Answer 7

Ardipithecus ramidus

Question 8

What can fossil skulls tell us about a species?

Answer 8

• diet
• age
• brainsize

Question 9

What are the six categories of fossil types?

Answer 9

• trace
• mould and cast
• replacement
• petrified or permineralized
• amber
• original material

Question 10

What is a

trace fossil?

and what are some examples?

Answer 10

any indirect evidence left by an organism

some examples are footprints, burrow and fossilized feces

Question 11

What are

mould and cast fossils?

Answer 11

a mould is an impression of an organism
a cast is a mould filled with sediment

Question 12

What are

replacement fossils?

Answer 12

fossils where the original material of an organism is replaced with mineral crystals that can leave detailed replicas of hard or soft parts

Question 13

What are

petrified or permineralized fossils?

Answer 13

empty pore spaces that are filled in by minerals

Question 14

What are

amber fossils?

Answer 14

Preserved tree sap that traps an entire organism. The sap hardens into amber and preserves the trapped organism.

Question 15

What are

original material fossils?

Answer 15

original organisms that have been preserved by mummification or freezing

Question 16

What are some of the problems that exist with using fossils solely as evidence for human evolution?

Answer 16

• fossils are very rare
• skeletons are often incomplete
• the specimen might be an anomolous case

Question 17

What are the 4 stages of classic fossilisation of a dinosaur?

Answer 17

1. Dinosaur dies
2. All soft tissues decay
3. Earth is layered on top
4. The bones become mineralised

Question 18

Define

genetic variation.

Answer 18

Individuals in a population vary in their characteristics as a result of differences in their genes.

Question 19

Explain

Darwin’s theory of evolution.

Answer 19

1. GENETIC VARIATION
   Individuals in a population vary in their characteristics as a result of differences in their genes.
2. COMPETITION
   Individuals compete for resources. Some variations are better adapted to getting recources than others.
3. NATURAL SELECTION
   Individuals with better-adapted variations are more likely to survive and reproduce.
4. INHERITANCE
   The next generation will contain more individuals with the ‘better adapted variations’.
5. EVOLUTION
   If the environment changes, natural selection will favour different variations. Over many generations, most of the individuals in the population will have the different ‘better adapted variations’. This may result in a new species.

Question 20

What are the 5 kingdoms in the

5 kingdom classification?

Answer 20

• plants
• animals
• fungi
• protists
• monerans

Question 21

Why has genetic analysis shown that some relationships in the 5 kingdom system were incorrectly identified?

Answer 21

Because the characteristics were similar due to adaptation to the same environment rather than inheritance.

Question 22

Why is

genetic evidence better than evidence from observable characteristics for classification?

Answer 22

DNA isn’t changed by the environment.

Question 23

What are the three domains of the three domain system?

Answer 23

• bacteria
• archaea
• eukaryota

Question 24

What is the kingdom in the bacteria domain?

Answer 24

enbacteria

Question 25

What is the kingdom in the archaea domain?

Answer 25

archaebacteria

Question 26

What are the kingdoms in the eukaryota domain?

Answer 26

- protista - fungi - plants - animals

Question 27

# Define selective breeding.

Answer 27

A technique where humans **control which organisms breed together** to **enhance** their **natural characteristics** for human use.

Question 28

# Define genetic engineering.

Answer 28

A process which involves **changing the DNA** of one organism by **inserting genes from another organism**. This creates **genetically modified organisms** and is another way to **introduce desirable characteristics** to organisms.

Question 29

# Define aseptic technique.

Answer 29

the process of keeping things sterile

Question 30

# What is tissue culture?

Answer 30

The **growing** of **cells or tissues** in a liquid containing nutrients or on a solid medium (such as nutrient agar). The **genetically identical cells** form a clump called a **callus**. These cells may be treated to **differentiate**.

Question 31

# Define callus.

Answer 31

a **clump** of **undifferentiated cells**

Question 32

# Define differentiate.

Answer 32

become specialised

Question 33

# Describe the stages of micropropagation.

Answer 33

1. A piece of **plant** is placed in **bleach** solution to **sterilise** it. 2. A small piece of **plant** is **cut off** and placed on **sterile nutrient medium** to grow. 3. The piece of plant is **treated** with **hormones** so that it grows **roots and shoots**. 4. When the plants are large enough, they are **planted** into soil or compost.

Question 34

# What are the positives of micropropagation?

Answer 34

- a **large number of plants** can be grown in a **short period of time** - **healthy plants** can be grown from **diseased plants** - plants **without seeds** can be multiplied - it is useful where **sexual reproduction** is not possible

Question 35

# What are the negatives of micropropagation?

Answer 35

there is **no variation** - a disease could wipe out the entire batch

Question 36

Why are **bacteria** very useful for **genetic engineering**?

Answer 36

- they have **plasmids** - they **reproduce asexually**

Question 37

# Define vector.

Answer 37

A vehicle for carrying **foreign DNA** into a cell. It is used to transfer **donor genes** into **recipient cells**.

Question 38

What is the most commonly used vector in genetic engineering?

Answer 38

a plasmid | and additional genes are added to it

Question 39

# What is recombinant DNA?

Answer 39

a **plasmid** which has had **genes** from **another organism inserted** into it

Question 40

# What are the different steps of humans insulin production?

Answer 40

1. There is a **human pancreas cell** containing DNA and a **bacterium** containing **bacterial DNA** and **plasmid DNA**. 2. The **human insulin producing gene** is cut out of the human pancreas cell using **restriction enzymes** to create **sticky ends**. 3. The **plasmid DNA** is cut out by the same technique to create **complementary sticky ends**. 4. The two types of DNAs are combined to form **recombinant DNA**. **Ligase enzyme** is used to seal the ends. 5. This **recombinant DNA** is **introduced** into a **bacterial cell**. 6. These bacterial cells are put into a **fermentation tank** so that they can multiply rapidly. 7. These **recombinant bacteria produce human insulin**. 8. The insulin is **extracted and purified**.

Question 41

# What are the benefits of genetic engineering in crops?

Answer 41

- the **nutritional value** of foods could be **improved** - crops can be produced that **lack** known **allergens** - crops can **grow** in **arid conditions** for **better yield** - genetically modified crops can **produce herbicides** to **kill pests** - **food supply**/agriculture can be **improved** in poor countries - genetically modified crops may have **longer shelf lives** - gowing **insect resistant genetically modified crops reduces** the amount of **chemical** used on crops to kill insects - growing **herbicide resistant genetically modified crops** makes it easier to **kill weed** but not crops - there is **no evidence of harm to health** from genetically modified crops so far - genes and proteins are broken down in the digestive system regardless of whether the food is genetically modified or not - **less spraying** is needed for **genetically modified crops** than for non-genetically modified varieties - economic costs and carbon footprint can be reduced because there is **less need for land clearing** and **pesticide** usage

Question 42

# What are the risks of genetic engineering in crops?

Answer 42

- new traits could cause **adverse health reactions** - removals of traits coud have **unkown effects** - crops may **limit biodiversity** of local environment - cross pollination could lead to **'super weeds'** - foods with genetically modified components **may not be labeled** - different governments may have **conflicting regulatory standards** concerning safe usage - growing **herbicide resistant** genetically modified crops means that farmers can **only use** the **herbicide** that the crop is **resistant to** - if the **insect resistance gene** was **transferred** to **weed** plants, insects would be killed eating wild plants as well as crops - insects could **evolve** to stop being affected by a particular herbicide - **genetically modified seed** is usually more **expensive** than non-genetically modified seed - new genetically modified seed must be bought each year

Question 43

# What is Bt Maize?

Answer 43

A **genetically modified Maize** crop that has a **bacterial gene** known as **Bt** (derived from the soild bacterium *Bacillus thuringiensis*) inserted into its genome. This gene produces a **protein** that is **toxic** to insect **pests**.

Question 44

# Define yield.

Answer 44

the **amount of food** we get from a crop