Topic 6 – Inheritance, Variation and Evolution

Question 1

What is the variation?

Answer 1

differences in the characteristics of individuals in a population

Question 2

What can cause variation?

Answer 2

genetic causes, environmental causes, and a combination of genes and the environment

Question 3

How do new phenotype variants occur?

Answer 3

mutations

Question 4

What is selective breeding?

Answer 4

breeding plants and animals for particular characteristics

Question 5

Describe the process of selective breeding.

Answer 5

1. choose parents with the desired characteristic
2. breed them together
3. choose offspring with the desired characteristic
4. continue over many generations until all offspring show the desired characteristic

Question 6

What are the consequences of inbreeding?

Answer 6

inherited defects and disease

Question 7

What is genetic engineering?

Answer 7

modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

Question 8

How have plant crops been genetically engineered?

Answer 8

to be resistant to disease/herbicides/pesticides, to produce bigger fruits, to give higher yields

Question 9

How have bacteria been genetically engineered?

Answer 9

to produce useful substances, such as human insulin to treat diabetes

Question 10

What are enzymes used for in genetic engineering?

Answer 10

cut out the required gene

Question 11

What is used to transfer the required gene into the new cell in genetic engineering?

Answer 11

vector( e.g., bacterial plasmid or virus)

Question 12

Describe the steps involved in adult cell cloning

Answer 12

1. nucleus removed from an unfertilised egg cell
2. nucleus from an adult body cell inserted into a cell
3. electric shock stimulates egg cells to divide to form an embryo
4. embryo develops and is inserted into the womb of an adult female

Question 13

What is tissue culture cloning?

Answer 13

using small groups of cells from plants to grow identical new plants

Question 14

Why is tissue culture cloning of plants important?

Answer 14

preserve rare species and for growing plants commercially in nurseries

Question 15

What is cutting as a cloning method?

Answer 15

simple method used by gardeners to produce many identical plants from a parent plant

Question 16

Describe cloning through using embryo transplants.

Answer 16

cells split apart from a developing animal embryo before they are specialised, then the identical embryos are transplanted into host mothers

Question 17

What is sexual reproduction?

Answer 17

joining(fusion) of male and female gametes

Question 18

What type of cell division is involved in sexual reproduction?

Answer 18

meiosis

Question 19

What type of cell division is involved in asexual reproduction?

Answer 19

mitosis

Question 20

What is meiosis?

Answer 20

cell division that produces four daughter cells (gametes), each with a single set of chromosomes

Question 21

What are the male and female sex chromosomes in humans?

Answer 21

XX-female, XY-male

Question 22

How can plants produce asexually?

Answer 22

bulb division (e.g.,daffodils) or runners (e.g.,strawberry plants)

Question 23

What is the genetic material in cells called?

Answer 23

DNA

Question 24

What is DNA?

Answer 24

polymer made of chains of four different nucleotides

Question 25

What does a nucleotides consist of?

Answer 25

sugar, phosphate group, and one of four different bases (A, G, C, or T)

Question 26

What is the structure of DNA?

Answer 26

two complementary strands of nucleotides forming a double helix

Question 27

What is a gene?

Answer 27

small section of DNA that codes for a particular amino acid sequence, to make a specific protein

Question 28

How many bases code for an amino acid?

Answer 28

three

Question 29

Which bases pair in complementary DNA strands?

Answer 29

C with G, T with A

Question 30

What is the function of non-coding DNA?

Answer 30

switch genes on and off to control their expression

Question 31

What are alleles?

Answer 31

different forms of the same gene

Question 32

What is recessive allele?

Answer 32

allele that needs to be present twice to be expressed

Question 33

What is a dominant allele?

Answer 33

allele that is always expressed, even if only one copy is present

Question 34

What is a genome?

Answer 34

the entire genetic material of an organism

Question 35

Define the term homozygous.

Answer 35

two of the same alleles present in an organism

Question 36

Define the term heterozygous.

Answer 36

two different alleles present in an organism

Question 37

Where in the cell are protein made?

Answer 37

on the ribosomes

Question 38

What type of allele causes polydactyly?

Answer 38

dominant allele

Question 39

What type of allele causes cystic fibrosis?

Answer 39

recessive allele

Question 40

How many chromosomes do normal human body cells have?

Answer 40

23 pairs

Question 41

What is evolution?

Answer 41

change in the inherited characteristics of a population over time through natural selection

Question 42

Who first proposed the theory of evolution by natural selection?

Answer 42

Charles Darwin

Question 43

What is the theory of evolution by natural selection?

Answer 43

all species of living things evolved from a common ancestor that developed billions of years ago

Question 44

Describe Lamarck's idea of inheritance.

Answer 44

organisms change over their lifetimes and these characteristics can be inherited

Question 45

Why was the theory of evolution by natural selection controversial?

Answer 45

- challenged the idea that God made all of Earth's animals and plants - insufficient evidence at the time - genes, inheritance, and variation were not understood

Question 46

What is speciation?

Answer 46

gradual formation of a new species as a result of evolution

Question 47

What evidence supports the theory of evolution?

Answer 47

- parents pass their characteristics to offspring in genes - fossil record evidence - evolution of an antibiotic-resistant bacteria

Question 48

What did Mendel discover through breeding experiments on plants?

Answer 48

inheritance of characteristics is determined by units (genes) passed on unchanged to offspring

Question 49

What are fossils?

Answer 49

remains of organisms from millions of years ago, found in rocks

Question 50

How might fossils be formed?

Answer 50

- parts of an organism do not decay because the conditions needed for decay are absent - traces of organisms are preserved - parts of an organism are replaced by minerals

Question 51

What are the problems with the fossil record?

Answer 51

- many early organisms were soft-bodied so left few fossils - gaps in the fossil record as not all fossils have been found and some have been destroyed

Question 52

What are the benefits of the fossil record?

Answer 52

can learn how species changed and life developed on Earth, and can track movement of species across the world

Question 53

What is extinction?

Answer 53

no individuals of a species are still alive

Question 54

What is the binomial system?

Answer 54

naming of organisms by their genus and a species

Question 55

What classification system did Carl Woese introduce?

Answer 55

three-domain system of Archaea, Bacteria, and Eukaryota

Question 56

Why can bacteria evolve rapidly?

Answer 56

they reproduce at a fast rate

Question 57

How do antibiotic-resistant strains of bacteria develop?

Answer 57

mutations that allow the strain to survive and reproduce