4- Inheritance and Selection

Question 1

how is DNA arranged?

Answer 1

• two STRANDS
• the strands are twisted around each other to form a DOUBLE HELIX
• the strands are held together by BONDS between BASE PAIRS

Question 2

where are chromosomes found?

Answer 2

in the nucleus

Question 3

how many chromosomes does each body cell have?

Answer 3

23 pairs of chromosomes, half of which are from each parent

Question 4

what is a species?

Answer 4

a group of similar organisms that can breed with another to produce fertile offspring

Question 5

what are ligers?

Answer 5

male lion and female tiger

Question 6

tigon

Answer 6

female lion and male tiger

Question 7

steps to select a particular feature in an organism

Answer 7

1. choose individuals with the desired feature
2. let only those individuals reproduce
3. choose offspring that have the desired feature
4. let only those individuals reproduce
5. repeat steps 3 and 4 until you have produced a variety of individuals that have the desired feature

Question 8

what are some examples of what selective breeding can produce?

Answer 8

• hens that lay eggs of a particular colour
• cattle that produce a lot of meat
• tomato plants that produce lots of tomatoes
• crops that are resistant to plant diseases

Question 9

what is variation?

Answer 9

the presence of differences between living things of the same species is called variation

Question 10

what is inherited variation?

Answer 10

variation in a characteristic that is a result of genetic info from the parents

Question 11

what are some problems that can lead to extinction?

Answer 11

• a new disease
• a new predator
• a change in the physical environment
• competition from another species that is better adapted

Question 12

what does the conservation of biodiversity assure?

Answer 12

• maintains the future possibility that plant species might be identified for medicines
• keeps damage to food chains and food webs to a minimum
• protects our future food supply