Evolution

Question 1

What Is Independent Assortment?

Answer 1

Independent assortment occurs during meiosis where the homologous chromosomes align along the equator of the cell, independent of each other. They then separate and different combinations of each are possible in the sex cells produced.

Question 2

What Is Crossing Over?

Answer 2

Crossing over is a process that occurs during meiosis where two homologous chromosomes pair up and exchange segments of their DNA. This causes variation in the sex cells produced.

Question 3

What Is Random Union Of Gametes?

Answer 3

Since there are so many different forms of sperm cells from a male individual and egg cells from a female individual, the resulting offspring of different combinations of these would look similar but not identical (like siblings).

Question 4

What Is A Mutation?

Answer 4

A mutation is a permanent change to the DNA sequence. (This is the only process that may introduce new genes.)

Question 5

Are All Characteristics In Humans Determined By One Gene?

Answer 5

No, there aren’t many examples of characteristics determined by one gene in humans and most are determined by several genes. E.g. height, weight, hair, skin colour.

Question 6

What Factors Affect The Variation In A Population Of Organisms?

Answer 6

The environment and the genetic make-up.

Question 7

What Is The Variation In Population, In Terms Of Natural Selection?

Answer 7

There is a variation in any population (e.g. long beak, medium beak, short beak).

Question 8

What Is Environmental Selection Pressure, In Terms Of Natural Selection?

Answer 8

Biotic agent and abiotic agents affect the ability of organisms to survive and reproduce.

Question 9

What Is Survival Of The Fittest, In Terms Of Natural Selection?

Answer 9

Those individuals with favourable characteristics are better adapted to that particular environment, and have a greater chance of survival.

Question 10

What Is Reproduction Of The Survivors, In Terms Of Natural Selection?

Answer 10

Those who survive, reproduce, and pass on the gene of their favourable characteristics.

Question 11

What Is Change In The Population, In Terms Of Natural Selection?

Answer 11

The population changes over time and has a greater proportion of individuals with favourable characteristics. The population as a whole is now better adapted to that particular environment.

Question 12

What Is An Abiotic Agent?

Answer 12

Abiotic factors are all the non-living things that interact with an organism. For example, temperature, light, humidity, the availability of air, water, and nutrients.

Question 13

What Is A Biotic Agent?

Answer 13

Biotic factors are all the living things that interact with an organism. For example, competition, availability of food, predators, and disease.

Question 14

What Is A Species?

Answer 14

A species is a group of living organisms consisting of similar individuals capable of interbreeding and producing fertile offspring.

Question 15

What Is Evolution?

Answer 15

Evolution is the process of change in the heritable characteristics of a population over time.

Question 16

What Is Embryological Evidence Scientists Use To Make
Inferences About Evolution?

Answer 16

Scientists often infer that due to the similarities of some organism’s embryos - specifically vertebrae - is that the genes that control the early growth may have come from common ancestors.

Question 17

What Is Comparative DNA Studies Evidence Scientists Use To Make
Inferences About Evolution?

Answer 17

Using DNA kits, evolutionary links can be established between various organisms, and an evolutionary tree can be constructed to show these links, and infer a common ancestor.

Question 18

What Is Fossil Evidence Scientists Use To Make
Inferences About Evolution?

Answer 18

Fossils are preserved remains of living organisms found in rocks. Older fossils are found in earlier rock layers, and young fossils are found in new rock layers, near the surface. From this, scientists compare fossils, and can infer that many organisms have a common ancestor.

Question 19

What Is Speciation?

Answer 19

Speciation is an evolutionary process that results in the formation of a new species from a pre-existing species.

Question 20

How Are Mutation And Selection Used To Explain The Changes In A Gene Pool Of A Population Which Might Result In The Formation Of A New Species (Specification)?

Answer 20

If populations of the same species are separated so that there is no gene flow between them, then mutation and natural selection may occur in isolation with different environmental selection pressures, leading to the formation of new species.

Question 21

What Is Evolutionary Trees?

Answer 21

Evolutionary trees are used to represent the evolutionary relationships between different organisms that have been inferred based on evidence.

Question 22

How Have Humans Applied Selection To Domesticate Many Species (E.g. Dog, Corn)?

Answer 22

They select those phenotypes in organisms that have a value or serve a purpose. This has changed the phenotypes of many different organisms. E.g. certain dog breeds were bred to find prey, like the cocker spaniel or the hound.

Question 23

How Is Insulin Made By Genetic Engineering?

Answer 23

The human insulin gene can be inserted into a bacterial chromosome so that large amounts of insulin can be made for people who have diabetes. Bacteria are used because they reproduce quickly and so make large qualities of insulin.

Question 24

What Are Some Of The Possible Benefits Of Producing Insulin Using Genetic Engineering?

Answer 24

It is a cost-efficient way of producing insulin.
It is faster at producing insulin.
The product produced is identical to what is produced in the human body.
Animals aren’t used to produce the human insulin hormone.

Question 25

Use The Example Of Antibiotic Resistance To Describe Natural Selection:

Answer 25

The variation in the population is individuals with a low, medium and high resistance to penicillin - all approximately equal.

The selecting agent was an abiotic agent - some individuals had a mutation where they had a low resistance to penicillin, meaning they were more likely to die when in contact with it.

Those individuals with a high resistance to penicillin were more likely to survive as they didn’t have a mutation which caused them to likely die if they came in contact with it. Those with medium/ low resistance were likely to die if they came in contact with penicillin.

Individuals who survived (high resistance) the penicillin, were more likely to survive to an age to reproduce, passing on the favourable gene to their offspring - high resistance to penicillin. Those who didn’t survive couldn’t reproduce, so their gene of medium/ low resistance couldn’t be passed on in this case.

Over time, the population changes from high, medium and low resistance to penicillin individuals to one that has a stronger proportion of individuals with high resistance, and none that have a medium/ low resistance. The population as a whole is now better suited to the environment, with penicillin in it.

Question 26

What Is The Process That Involves Mammals Being Cloned?

Answer 26

A clone has the identical genotype of its sole parent.
1. The egg is taken from one individual. The nucleus is removed to make a blank egg.
2. The nucleus is taken from a body cell of a different individual of the same species to be cloned.
3. Donor DNA and blank egg fuse.
4. Cell division occurs, replicating the egg with new DNA.
5. Cells separate into many embryos.
6. Embryo implanted into surrogate female.
7. identical offspring (clone) is produced, each containing the same genes as the animal that donated the DNA.

Question 27

What Are The Advantages And Disadvantages Of Cloning?

Answer 27

Advantages:
Guaranteed quality of product (e.g. wool, meat).
Large numbers of individuals produced quickly

Disadvantages:
High cost
Entire population is vulnerable to the same disease-causing organisms.