bio chapter 6

Question 1

Formation:

Question 2

1. Parts that do not decay due to a lack of oxygen or moisture.

Question 3

2. Parts replaced by minerals.

Question 4

3. Preserved traces like footprints.

Question 5

Extinction:

Question 6

• When a species no longer exists.

Question 7

Causes:

Question 8

1. Environmental changes.

Question 9

2. New predators.

Question 10

3. New diseases.

Question 11

4. Competition for food.

Question 12

5. Catastrophic events.

Question 13

Classification

Question 14

Linnaean System:

Question 15

• Developed by Carl Linnaeus.

Question 16

Organisms classified into kingdom

Answer 16

phylum

Question 17

species.

Question 18

Evolutionary Trees

Question 19

• Show how closely related organisms are

Answer 19

using fossil records and classification data.

Question 20

Ethical Considerations:

Question 21

•

Question 22

For: Reduces suffering

Answer 22

treating disorders is expensive.

Question 23

•

Question 24

Against: Could lead to designer babies

Answer 24

promotes prejudice

Question 25

Evolution and Natural Selection

Question 26

• Evolution is a change in inherited traits over time

Answer 26

driven by natural selection.

Question 27

Key Points:

Question 28

1. Mutations create variation.

Question 29

2

Question 30

Mutations providing a survival advantage are passed on.

Question 31

3. Over generations

Answer 31

these mutations increase in frequency.

Question 32

4. Speciation: One population becomes different enough to form a new species.

Question 33

Selective Breeding

Question 34

• Humans breed organisms for desired characteristics.

Question 35

Process:

Question 36

1. Select parents with the desired trait.

Question 37

2. Breed them and select offspring with the trait.

Question 38

3. Repeat over many generations.

Question 39

Problems: Can cause inbreeding

Answer 39

reducing the gene pool and making species more

Question 40

vulnerable to disease or environmental changes.

Question 41

Genetic Engineering

Question 42

• Modifying the genome by introducing a gene from another organism.

Question 43

Examples:

Question 44

• Plants engineered for disease resistance or larger fruits.

Question 45

• Bacteria engineered to produce human insulin.

Question 46

Fossils and Extinction

Question 47

Fossils:

Question 48

• Fossils are remains of organisms from millions of years ago

Answer 48

found in rocks.

Question 49

• Alleles: Different forms of a gene; humans inherit two alleles (one from each

Question 50

parent).

Question 51

•

Question 52

Dominant allele: Only one copy is needed for the trait to show.

Question 53

•

Question 54

Recessive allele: Two copies are needed for the trait to show.

Question 55

• Homozygous: Both alleles are the same (e.g.

Answer 55

AA or aa).

Question 56

• Heterozygous: One dominant and one recessive allele (e.g.

Answer 56

Aa).

Question 57

• Genotype: The combination of alleles (e.g.

Answer 57

Aa).

Question 58

• Phenotype: The physical traits or characteristics (e.g.

Answer 58

eye colour).

Question 59

Punnett Squares

Question 60

• Used to predict the probability of offspring inheriting certain genotypes and

Question 61

phenotypes.

Question 62

• Dominant characteristics are shown by uppercase letters (e.g.

Answer 62

A) and recessive by

Question 63

lowercase (e.g.

Answer 63

a).

Question 64

BB

Question 65

BB

Question 66

I moners

Question 67

alleles

Question 68

b

Question 69

Bb

Question 70

Bb

Question 71

fathers

Question 72

alleles

Question 73

Genetic Disorders

Question 74

• Polydactyly: Extra fingers or toes (caused by a dominant allele).

Question 75

•

Question 76

Cystic Fibrosis: A disorder affecting cell membranes

Answer 76

resulting in thick mucus in

Question 77

airways and pancreas (caused by a recessive allele).

Question 78

Embryonic Screening

Question 79

• Used to screen embryos for genetic disorders.

Question 80

• Cells are taken from embryos (in a lab or womb) and analysed for specific alleles.

Question 81

What is sexual reproduction?

Answer 81

Involves the joining of male and female gametes, each containing genetic information from the parents

Question 82

How are gametes formed?

Answer 82

By meiosis (non-identical cells)

Question 83

What are the gametes in animals and flowering plants?

Answer 83

* Sperm and egg cells in animals * Pollen and egg cells in flowering plants

Question 84

How many chromosomes do gametes contain?

Answer 84

23 chromosomes each

Question 85

What happens during fertilisation?

Answer 85

Gametes fuse to form a zygote with 46 chromosomes (23 pairs)

Question 86

What causes variation in offspring?

Answer 86

The mixing of genetic information

Question 87

What is asexual reproduction?

Answer 87

Involves only one parent and no gametes

Question 88

How does asexual reproduction occur?

Answer 88

By mitosis (two identical cells are formed)

Question 89

What type of offspring results from asexual reproduction?

Answer 89

Clones, genetically identical to the parent

Question 90

Give examples of organisms that reproduce asexually.

Answer 90

* Bacteria * Some plants * Some animals

Question 91

What is meiosis?

Answer 91

Cell division that produces four non-identical gametes with half the number of chromosomes (23)

Question 92

What is mitosis?

Answer 92

Cell division that produces two identical body cells with the same number of chromosomes (46)

Question 93

What is the key difference between meiosis and mitosis?

Answer 93

Meiosis results in genetic variation, while mitosis creates identical copies of cells

Question 94

Define gamete.

Answer 94

Reproductive cell with half the chromosomes (23)

Question 95

Define chromosome.

Answer 95

Structure in the nucleus made of long strands of DNA

Question 96

Define gene.

Answer 96

A section of DNA that codes for a protein, contributing to characteristics