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Flashcards in AS Level Unit 2 Deck (134):
0

What is the middle of a chromosome called?

Centromere

1

What are homologous chromosomes?

A pair of chromosomes, one from paternal and one from maternal with the same genes but different alleles

2

Name two ways in which meiosis allows the production of genetically different cells

Crossing over and independent segregation

3

What is a species?

A group of similar organisms that can reproduce to produce fertile offspring

4

A forest was cleared. Why did species diversity decrease?

Decrease in the variety of plants, fewer habitats and a decrease in food sources

5

What is a hierarchy?

Groups within groups and no overlaps between the groups

6

What is a phylogenetic group?

Grouped according to evolutionary relationships

7

Why is cytochrome C more useful than haemoglobin for studying how closely related different organisms are?

The structure of cytochrome C is similar in all organisms

8

How can antibiotics prevent the growth of bacteria?

Prevent a formation of the cell wall

9

Describe how bacteria can become resistant to antibiotics by vertical gene transmission

The genes are transmitted through cell replication

10

Why did doctors take a sample from many patients in the hospital?

So it's representative

11

What causes root pressure?

active transports of salts by the endodermis

12

Name a type of reaction that breaks down carbohydrates into their monomers?

Hydrolysis

13

Why is an arteriole described as an organ?

Made up of more than one tissue

14

Name all of the stages of taxonomy

Kingdom, phylum, class, order, family, genus and species

15

What is intraspecific variation?

differences within a species

16

Give two reason why the potometer does not truly measure the rate of transpiration

Water is used for support and water is used in photosynthesis

17

What is species diversity?

The total number of individuals in each species and the total number of individuals of all species

18

How does carbon dioxide in the air outside of the leaf reach Mesophyll cells inside of the leaf?

Carbon dioxide enters via the stomota and diffuses through air spaces down a concentration gradient

19

What monomers form a cellulose molecule?

Beta glucose

20

What bonds join a cellulose molecule

Glycosidic bonds

21

Why is mitosis important in the life of an organism?

For growth and repair of cells and for asexual reproduction

22

Why is DNA a polymer?

More than one nucleotide

23

Name the three parts of DNA molecule

Hydrogen bonds, deoxyribose sugar and phosphate group

24

What does standard deviation show? 2 marks

The variation of data around the mean
No overlap means that it is not due to chance

25

Name three parts of a chloroplast

Granum, stroma and thylakoids

26

Give two ways in which courtship increases the probability of successful mating

Species recognition
Sexual maturity

27

How do bacteria become resistant strains?

A random mutation occurs, so resistant gene so the resistant bacteria survives and reproduces

28

How is the resistant gene passed on from one species of bacteria to another?

By horizontal gene transmission via conjugation where they plasmid/circular DNA is copied

29

What is genetic diversity?

Differences in DNA

30

Explain the advantage of cells completing the cell cycle in a short time

They can multiply rapidly

31

What is interspecific variation?

Differences between different species

32

Name an animal cell and its 2 adaptations

Squamous epithelial cell
Thin cytoplasm for a short diffusion pathway
It's long so it's got a large surface area

33

What are the lungs made up of? 3

Squamous epithelial tissue
Fibrous connective-tissue
Blood vessels

34

What four things is the respiratory system made up of?

Lungs, trachea, bronchi and diaphragm

35

What is squamous epithelial tissue is made up of?

Epithelial cells

36

Name a plant cell

Palisade Mesophyll cell

37

How is the palisade Mesophyll cell adapted for photosynthesis?

It's got many chloroplasts and the large vacuole pushes the cytoplasm and chloroplasts to the edge of the cell

38

What two things are xylem tissue made up of?

Xylem vessels and parenchyma cells

39

What four things are leaves made up of?

Xylem and phloem, epidermis tissue and Mesophyll tissue

40

Name the four things that make up the shoot system

Leaves, buds, stems and flowers

41

What is the role of starch?

For energy storage in plants

42

Why is it good that is insoluble?

So water potential doesn't affect the cell so it won't swell and burst

43

What monomers is starch made up of and what bonds is it joined by?

Alpha glucose and glycosidic bonds

44

What is the structure of amylose?

Coiled so it's good for storage because it's compact

45

What is the structure of amylopectin and why is this good?

Long branched so enzymes can reach bonds quickly to release energy

46

What is the role of glycogen?

For energy storage in animals

47

What's monomers is glycogen made up of and what bonds are they joined by?

Alpha glucose and glycosidic bonds

48

What is the structure of glycogen?

Short branched so it is good for storage because it's compact

49

Will enzymes reach the bonds in starch or glycogen quicker?

Glycogen

50

What is the role of cellulose and where is it found?

Provides rigidity for structural support and it's in plant cell wall

51

What is the structure of cellulose? Three marks

Long unbranched, held together by hydrogen bonds bonds, forming microfibrils

52

In cellulose, how are the glucose monomers arranged?

Alternating glucose molecules rotated by 180°

53

How are glucose monomers arranged in starch?

The same way up

54

Name three parts of the liver in order

Hepatic vein, hepatic portal vein and hepatic artery

55

What are the two parts of the kidney in order?

Renal vein and renal artery

56

During which parts of the cell cycle are gene mutation is most likely to occur?

Interphase

57

What is an allele?

A different variation of a Gene

58

Describe two features of the appearance of a chromosome

Two sister chromatids joined by a centromere

59

Suggest why only a few gametes only have a new combination of the new alleles

It's rare and infrequent

60

Comparing the base sequence of a gene provides more information than comparing the amino acid sequence for which the gene codes. Explain why.

Intron/non-coding DNA
Longer base sequence than amino acid sequence

61

How many bases code for an amino acid and what is this called?

Three bases
Triplet code

62

What is crossing over?

The exchange of alleles between chromosomes

63

How is tissue fluid formed? 3 marks

High hydrostatic pressure forces water out of the capillary but leaves behind large proteins

64

How is tissue fluid returned to the circulatory system? 4 marks

There is a lower water potential in the capillary
due to plasma proteins
so water enters into the capillary by osmosis from high water potential to lower water potential
and the rest is returned by the lymphatic system

65

What is the Bohr affect?

That haemoglobins oxygen affinity is inversely related to the concentration of carbon dioxide

66

Describe what happens in DNA replication. 8 marks

1. DNA Helicase
2. Causes hydrogen bonds to break, separating the DNA strands
3. Each strand acts as a template
4. Free nucleotides attach to each strand
5. They are complementary base pairing (AT, CG)
6. DNA Polymerase joins nucleotides onto new strand
7. Hydrogen bonds reform
8. Known as semiconservative model as one strand is new and one strand is old

67

What five things happen in prophase?

1. Chromosomes condense
2. Centrioles move to opposite poles of the cell
3. Spindle fibres form
4. Nuclear envelope breaks down
5. Chromosome lie free in the cytoplasm

68

What two things happen during metaphase?

1. Chromosomes line up along the Equator of the cell
2. Spindle fibres attach to the centromeres

69

What three steps happen during anaphase?

1. Centromere divide, separating sister chromatids
2. Spindle fibres contract, pulling chromatids to opposite poles of the cell
3. Centromere first

70

What three things happen during Telophase?

1. Chromatids reach the opposite poles of the cell and uncoil
2. Nuclear envelope reforms around each set of chromosomes
3. Cytoplasm divides

71

What is produced at the end of mitosis?

Two genetically identical daughter diploid cells

72

What do you get at the end of Meiosis?

Four genetically unidentical daughter haploid cells

73

What is cancer?

The uncontrolled division of cells

74

How does radiation help treat cancer? 4 marks

1. Damages DNA
2. During S phase DNA is checked for damage
3. Damaged it DNAs stop cell replication and kills cell
4. Preventing tumour growth

75

How does chemotherapy help prevent cancer? 3 marks

1. Effects enzymes involved in DNA replication
2. Stops S-phase and cell kills itself
3. Preventing tumour growth

76

How does surgery help treat cancer? 3 mark

1. Remove part of the tumour
2. Activates the cell cycle
3. Making radiation and chemotherapy more effective

77

What blood does arteries and arterioles transport?

Oxygenated

78

Name three features of the artery and what it does

1. Smooth muscle to contract for vascoconstriction to change blood flow and pressure
2. Elastic tissue to stretch under pressure and recoil to even out the pressure
3. Smooth epithelium to prevent friction to reduce blood clots

79

What is the role of capillaries?

For exchange

80

Name three features of the capillary and what they do

1. Small lumen to slow substances so more time for exchange
2. One cell thick for a short diffusion pathway
3. Large surface area from a large network of capillaries

81

What blood do veins transport?

Deoxygenated

82

Name three features of a vein and what they do

1. Valves prevent the back flow of blood
2. Body muscles contract to maintain blood flow
2. Wide lumen for low pressure

83

An increasing respiration in the tissues of a mammal affects the oxygen disassociation curve of haemoglobin. Describe and explain how

There is more carbon dioxide so the curve moves to the right

84

How are single celled organisms adapted for gas exchange? 2 marks

A large surface area to volume ratio and a thin surface so short diffusion pathway

85

What system do insects use?

Tracheal system

86

In insects, what does abdominal pumping do?

Get oxygen in quicker, so a steeper concentration gradient

87

How do insects have a large surface area?

Vast network of trachea and trachioles

88

How do insects have a short diffusion pathway?

The trachea have thin permeable walls

89

How do insects maintain concentration gradient?

By the spiracles opening and closing

90

In what two ways do insects prevent water loss?

They have a waterproof waxy cuticle and they close the spiracles

91

How do fish have a large surface area?

The gill filaments and lamellae are at 90° right angles

92

How do fish maintain concentration gradient?

The counter current flow where the blood and water move in opposite directions

93

How do fish have a short diffusion pathway?

Thin epithelium cells

94

What do plants need for respiration?

Oxygen

95

What do plants need for photosynthesis?

Carbon dioxide

96

What gives leaves a large surface area?

Mesophyll cells

97

How do leaves have a short diffusion pathway?

The stomata opens

98

How do leaves maintain a concentration gradient?

By respiration, photosynthesis and stomata opening

99

What three substances need exchanging?

Respiratory gases, urea and heat

100

What circulatory system do mammals have?

A double circuit where blood passes through the heart twice

101

What ratio do large mammals have?

Small surface area to volume ratio

102

How does water move into the roots

Lower water potential in roots that soil due to amino acids and sugars, so water moves in from high to low water potential by osmosis

103

How does water move across apoplastic pathway?

Moves through nonliving cell wall using cohesion between water molecules until it reaches the casparian strip, where it is forced into the symplastic pathway

104

How does water move through the symplastic pathway?

Through the living cytoplasm by osmosis from high to low potential through the plasmadesmata

105

How does water move into the xylem?

Active transport by endodermis of salts into the xylem known as root pressure. Lowers water potential, so moves from high to low water potential into xylem

106

How does water move up xylem?

Evaporation/transpiration from the leaves
Create cohesion and tension between water molecules by hydrogen bonds
Adhesion/ water molecules bind to xylem
Creating continuous water column

107

What are the four factors that affect transpiration?

Temperature, light intensity, air movement and humidity

108

What three ways plants prevent water loss?

Sunken stomata in pits, layer of hairs on epidermis, Waxy waterproof cuticles

109

In tissue fluid, what is the right hand side of the capillary end called?

Arteriole end

110

In tissue fluid, what is the left hand side of the capillary called?

Vein end

111

What photosynthetic pigment is in the thylakoids?

Chlorophyll

112

What is an intron?

Amino acids that don't code for proteins and is removed during protein synthesis

113

What is an exon?

Amino acids that do code for proteins

114

What is a mutation?

A random change in the base sequence of DNA

115

Where are genes found?

A locum on a section of DNA

116

What is a gene?

A section of DNA that code for polypeptides that affects nature and development

117

Name the two specific organic base pairings

Adenine & Thymine
Cytosine & Guanine

118

What do the organic bases contain?

Nitrogen

119

How many hydrogen bonds do guanine and cytosine have?

Three

120

How many hydrogen bonds do adenine and thymine have?

Two

121

Name three things that can affect genetic diversity

Genetic bottlenecks, founder effect and selective breeding

122

What does a decrease in diversity lead to?

Reduction in the variety of alleles

123

Name two advantages of selective breeding

Produce a higher yield of animals and plants
Produce organisms that are resistant to disease and have a high tolerance to bad conditions

124

Give two disadvantages of selective breeding

The welfare of the animals is at risk
Reduces genetic diversity so more risk of genetic diseases

125

What structure is DNA?

Double helix

126

Why can't antibiotics be used for viruses?

Viruses don't have a cell wall

127

What is osmotic lysis?

The cell wall is not formed, so there is a lower water potential in the bacteria, so water enters by osmosis to expand the cell and burst

128

What three ways can we prevent the occurrence of antibiotic resistance?

Make sure antibiotics prescribed when necessary
Make sure all courses of antibiotics are finished
Ensure hygiene by using antiseptic gel

129

What are three advantages of using antibiotics that are ethical reasons?

Prevent suffering
Everybody has the right to medication
Improves quality of life

130

Give three disadvantages that are ethical reasons of using antibiotics

Should be only saved for life threatening diseases
Shouldn't treat the terminally ill
Increases antibiotic resistance

131

Give two reasons why it is difficult to define species

Some species are extinct so there is no fossil record
There is lots of variation within species such as different breeds of dogs

132

Describe DNA hybridisation

1. DNA from two species heated
2. To separate single strands
3. Strands mixed together
4. Strands join by complimentary base pairings
5. Forming hydrogen bonds
6. The more bonds that hybridise, the more similar the DNA is
7. Heat again
8. The higher the temperature needed, the more energy needed to break the bonds
9. The more bonds, they more similar the DNA so the more closely related species are

133

Describe immunology

1. Similar proteins will bind to the same antibodies
2. Remove the protein such as albumin from the first species
3. Inject the protein into the second species
4. Inject the antibodies produced into other species
5. If antibodies bind to any proteins then it will create a precipitate
6. More precipitate than the more closely related species are