B6 - Inheritance, Variation and Evolution 2

Question 1

What is variation

Answer 1

Differences in the characteristics of individuals in a population

Question 2

What is environmental variation

Answer 2

Differences between members of the same species that have been caused by the environment it lived/lives in

Question 3

What is a mutation

Answer 3

Rare and random change in DNA that can be inherited

Question 4

What did Charles Darwin come up with and what does it mean (3marks)

Answer 4

‘Survival of the fittest’ - Organisms with the most suitable characteristics for the environment would be more successful competitors and would be more likely to survive

Question 5

What is evolution (3 marks)

Answer 5

a change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species

Question 6

What happens if two populations of one species become so different in phenotype and what is this called

Answer 6

They can no longer interbreed to produce fertile offspring they have formed two new species.
Speciation

Question 7

What is the theory of evolution

Answer 7

All of today’s species have evolved from simple life forms that first started to develop over three billion years ago

Question 8

Give 5 reasons why species go extinct

Answer 8

Environment changes too quickly
New predator kills them all
New disease kills them all
Can’t compete with another new species for food#
Catastrophic event that kills them all

Question 9

What is selective breeding

Answer 9

When humans artificially select the plants or animals that are going to breed so that the genes for particular characteristic remain in the population

Question 10

Give four examples of uses of selective breeding

Answer 10

animals that produce more meat or milk
crops with diseases resistance
dogs with a good, gentle temperament
decorative plants with big or unusual flowers

Question 11

Explain how selective breeding is used in agriculture (4 marks)

Answer 11

Can be used to improve yields
E.g. improve meat yields, a farmer could breed together cows and bulls with the best characteristics for producing meat (large size) - after several generations the farmer would get cows with very high meat yield

Question 12

Describe the drawbacks of selective breeding (4 marks)

Answer 12

reduces gene pool in a population - farmer keeps breeding from the “best” animals/plants that are all closely related
Inbreeding can cause health problems because there’s more chance of the organism inheriting harmful genetic defects when the gene pool is limited
If a new disease appears, all stock closely related to each other will most likely be killed if one of them dies

Question 13

What is genetic modification

Answer 13

Process that involves modifying an organism’s genome by introducing a gene from another organism to give a desired characteristic.

Question 14

Give four examples of genetic modification (6 marks)

Answer 14

Bacteria genetically modified to produce human insulin - treat diabetes
GM crops - improve the size and quality of their fruit/ make them resistant to disease, insects, and herbicides
Sheep have been genetically modified to produce substances like drugs in their milk to treat human diseases
Research for treatments for inherited diseases caused by faulty genes

Question 15

What is meant by the term gene therapy

Answer 15

inserting working genes into people with a inherited disease

Question 16

What are the advantages of GM crops (3 marks)

Answer 16

Increase the yield to make more food
People living in developing countries lack nutrients in their diets, GM crops engineered to contain the missing nutrient
GM crops are already being grown in some places without any problems

Question 17

Describe the main steps of Genetic Engineering
(4 marks)

Answer 17

enzymes are used to isolate the required gene; this gene is
inserted into a vector, usually a bacterial plasmid or a virus
* the vector is used to insert the gene into the required cells
* genes are transferred to the cells of animals, plants or
microorganisms at an early stage in their development so that they develop with desired characteristics.

Question 18

What are the disadvantages of Genetic Modification(4 marks)

Answer 18

Belief of GM crops will affect the number of wild flowers that live in and around the crops - reducing farmland biodiversity
Not everyone is convinced GM crops are safe and some people are concerned that we might not fully understand the effects of eating them on human health
Transplanted genes may get out into the natural environment

Question 19

Describe how fossils are formed through gradual replacement by minerals (3 marks)

Answer 19

Teeth, shells, bones which don’t decay easily
Eventually replaced by minerals as they decay forming rock-like substance shaped like the original hard part
Surrounding sediments also turn to rock but the fossil stays distinct inside the rock and eventually someone digs it up

Question 20

Describe how fossils form from casts and impressions (4 marks)

Answer 20

Fossils are formed when an organism is buried in a soft material like clay
Clay later hardens around it and the organism decays, leaving a cast of itself
An animals burrow or a plants root can be preserved as casts
Things like footprints can also be pressed into these materials when soft, leaving an impression when it hardens

Question 21

Describe how fossils form from preservation in places where no decay happens
(3 marks)

Answer 21

In amber and tar pits there is no oxygen or moisture so decay microbes
In glaciers it’s too cold for decay microbes to work
Peat bogs are too acidic for decay microbes

Question 22

Describe what a fossil is fr..

Answer 22

Fossils are the ‘remains’ of organisms from millions of years ago, which are found in rocks

Question 23

Describe why hypotheses of how life began can’t be supported or disproved
(3 marks)

Answer 23

Many early forms of life were soft-bodied and soft tissue tends to decay away completely - fossil record is incomplete
Fossils that did form millions of years ago may have been destroyed by geological activity

Question 24

Describe how antibiotic resistance arises (4 marks)

Answer 24

A population of bacteria infects someone
Person takes antibiotics to kill bacteria
Some bacteria have/get a random mutation that makes them susceptible to antibiotics than others
Antibiotic kills kill all other bacteria except those that are resistant
Bacteria grows rapidly - more mutations arise - greater resistance

Question 25

Give 3 ways to reduce the rate of antibiotic resistance

Answer 25

Doctors should not prescribe antibiotics in cases that is not necessary - mild bacterial infections/viral infections
Patient should take the full course of the antibiotics
Agricultural use of antibiotics should be restricted

Question 26

Explain why it is important that people take the full course of antibiotics they are prescribed

Answer 26

Ensures all bacteria is destroyed - none left to mutate and develop antibiotic-resistant strains

Question 27

Explain why drug companies are unable to develop new antibiotics effective against resistant strains (2 marks)

Answer 27

The development of new antibiotics is costly and slow. It is unlikely to keep up with the emergence of new resistant strains.

Question 28

Who created classification system and what are the different kingdoms

Answer 28

Carl Linnaeus
kingdom, phylum, class, order, family, genus, species

Question 29

What are the three domain system and who created it

Answer 29

Archaea - primitive bacteria usually living in extreme places such as hot springs and salt lakes
Bacteria - true bacteria
Eukaryota - fungi, plants, animals and protists
CARL WOESE!

Question 30

What is the binomial system

Answer 30

Name = genus + species

Question 31

acronym for linnaeus’ bs classification

Answer 31

KILL PAK1S CUZ OF FAMILY GAI SEGS
kingdom, phylum, class, order, family, genus, species