Variation, Reproduction, and New Technology

Question 1

What are chromosomes?

Answer 1

Thread-like structures that carry genetic information

They are found in the nucleus of a cell

Question 2

What are genes?

Answer 2

Short sections of DNA carrying genetic information

Chromosomes are made up of lots of genes

Question 3

What are gametes?

Answer 3

Sex cells with only half the genetic material/chromosomes of a normal cell

Question 4

How is genetic information passed on?

Answer 4

From parents to offspring through reproduction.

The offspring contain two sets of genes, inherited from both parents

Question 5

What do genes control?

Answer 5

The development of different characteristics of offspring

Question 6

How are chromosomes found in most body cells?

Answer 6

In pairs.

One set from the mother, one from the father

Question 7

What is asexual reproduction?

Answer 7

Reproduction that involves only one individual with no fusing of gametes to produce offspring

The offspring are identical to the parent. These are known as clones

Question 8

What are clones?

Answer 8

Offspring produced by asexual reproduction which are identical to the parent

Question 9

What is sexual reproduction?

Answer 9

Reproduction involving the fusion of male + female gametes

This produces genetic variety in the offspring

Question 10

Offspring produced by sexual reproduction can be similar but not identical to parents. Why?

Answer 10

Because they have a combination of two sets of genes

Question 11

What causes the variation in sexual reproduction?

Answer 11

The random mixing of genes

Question 12

Why is variation important to survival?

Answer 12

Because some genes may give offspring a better change of survival

Question 13

What causes differences in the characteristics of individuals of the same species?

Answer 13

• Genes they have inherited
• The conditions in which they have developed (environment)
• A combination of both

Question 14

What is the most important factor in determining the appearance of an individual?

Answer 14

Genes

Question 15

What might affect the characteristics/development of a plant?

Answer 15

• Lack of light
• Lack of nutrients
• Lack of space to grow
• Genes

Weaker plants may have the same genes as healthier ones but cannot grow well due to a lack of nutrients

Question 16

What might affect the characteristics/development of a human?

Answer 16

May be affected during pregnancy:

• If a mother drinks alcohol
• If the mother smokes

These lead to a smaller birth weight

Question 17

What might affect the characteristics/development of an animal?

Answer 17

• Too much/little food
• Genes
• Training muscles (to be an athlete vs. a predisposition towards being ripped)

Question 18

Why/where is cloning useful?

Answer 18

To produce new individuals that are useful in farming and agriculture

This could be more like ‘Never Let Me Go’ or just cloning tasty potatoes

Question 19

How can plants be clones?

Answer 19

• Taking cuttings of a mature plant + growing them
• Taking small groups of cells from a part of the plant and growing them under special conditions. This is called tissue culture

Question 20

What are the advantages/disadvantages of the different methods of cloning plants?

Answer 20

• Taking cuttings is cheap, easy, and quick
• It’s not as reliable
• Tissue culture can produce large numbers of rare/top quality plant
• However, it is more expensive

Question 21

How are animals cloned?

Answer 21

• Through embryo transplants
• An embryo of unspecialised cells is split into smaller groups of cells
• Each group of geneticall identical cells is transplanted + allowed to develop in the host animal

Question 22

What might happen to a plant/animal before it is cloned?

Answer 22

It might be genetically modified to produce useful substances

Question 23

What is taking a cutting an artificial form of?

Answer 23

Asexual reproduction

Question 24

What is adult cell cloning?

Answer 24

The process in which the adult cell from an animal is fused with an empty egg of another

The embryo created is then placed in the uterus of a third animal.

Question 25

Describe the process of adult cell cloning

Answer 25

* The nucleus is removed from an unfertilised egg cell * The nucleus of an adult cell (of the animal that will be cloned) is placed inside the 'empty' egg cell * The new cell is given a mild electric shock, causing it to begin to divide. * The ball of cells formed is called an embryo, and is genetically identical to the adult cell it originated from * Once the embryo has developed, it is implanted into the uterus of a host animal

Question 26

Give an example of an animal produced by adult cell cloning

Answer 26

Dolly the sheep in 1997

Question 27

What are the advantages of adult cell cloning?

Answer 27

* Can save animals from extinction * Has led to the development of genetically engineered animals that produce valuble proteins in their milk * These can be used in medicine

Question 28

What are the disadvantages of adult cell cloning?

Answer 28

* Ethical concerns * Limits variation of population/gene pool. This can become a problem for natural selection/genetic diseases/breeding * Concerns about using the technique on humans in the future

Question 29

What is genetic engineering?

Answer 29

Changing the genetic information/make-up of a cell/organism

Question 30

How is genetic engineering carried out?

Answer 30

* Genes can be transfered to the cells of plants, animals, or microorganisms during the **early stages of their development** * A gene is '**cut out**' of a chromosome using an **enzyme**. It is then placed in the chromosome of another organism. * The genes may be placed in an organism of the **same species** to give the **'desired' characteristic** * Or, they may be placed into a **different species**, e.g. a bacterium. * The gene used to produce **insulin** in humans can be implanted into **bacteria** so that they generate large quantities of it to treat people with diabetes.

Question 31

Why is it more difficult to successfully clone animals than plants?

Answer 31

* Animal embryo cells must be **split into groups of cells** before each group can be transfered to the host mother * There have to be enough hosts and some embryos **may die during development** * It also **takes longer** for animals to develop.

Question 32

What are crops with changed/altered genes called?

Answer 32

Genetically modified

Question 33

What are the advantages of genetic engineering and cloning?

Answer 33

* Cloning can produce herds of cattle with **useful characteristics** * Adult cell cloning may be used to **make copies of the best animal** (e.g. horses) * Genetic engineering can be used to **prevent/cure genetic disorders** * **Medical drugs** can be produced by genetic engineering e.g. insulin + antibodies * GM crops can be **resistant to herbicides or pesticides** * Gm crops have a **higher yield**

Question 34

What are the disadvantages of genetic engineering and cloning?

Answer 34

* GM crops need to be purchased every year because they are **infertile** * There are concerns about **cross-pollination** with wild flower populations * **Insects which are not pests** may be affected by the **pesticides** used on GM crops * Concerns about the effects of **eating GM** crops on human **health** * **Ethical** concerns * **Long-term** effects unknown * Will we **create new organisms** we know nothing about?