BIOLOGY PART 1 and 2 Flashcards Preview

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Flashcards in BIOLOGY PART 1 and 2 Deck (216):
1

Animal cells contain

Nucleus
Cell membrane
Cytoplasm
Mitochondria
Ribosomes

2

Plant cells contain

Nucleus
Cell membrane
Cytoplasm
Mitochondria
Ribosomes
Cell wall
Chloroplasts
Vacuole

3

Nucleus

Contains DNA and controls cell activity, and instructions for making new cells/organisms

4

Cell membrane

Controls what goes in and out of the cell

5

Cytoplasm

Liquid gel in which chemical reactions take place e.g. Respiration

6

Mitochondria

Structures in the cytoplasm where energy is produced during respiration

7

Ribosomes

Where protein synthesis takes place (making proteins from amino acids)

8

Cell wall

Made from cellulose to strengthen and supports the cell

9

Chloroplasts

Found in green parts of plants. Contains chlorophyll which absorbs light energy to make food by photosynthesis

10

Bacterial cells contain

Cytoplasm
Cell membrane
Cell wall
Loop of DNA
Capsule

11

Loop of DNA

Controls the cell, as bacterial cells do not have a nucleus

12

Capsule

Slimy capsule around outside of cell wall to protect it from antibiotics

13

Fungal cells are ... than bacterial cells

Larger, and can be seen using a light microscope

14

A fungal cell wall is made of

Chitin

15

Why were bacterial cells discovered later?

Not enough advanced technology
Bacterial cells are much smaller

16

Yeast cells are a

Single celled organism

17

Yeast cells contain

Nucleus
Cytoplasm
Cell membrane
Ribosomes
Mitochondria
Cell wall

18

Palisade cell (from a leaf)

Absorbs light for photosynthesis
Contains chloroplasts which contain the pigment chlorophyll

19

Muscle cell

Contracts to provide movement
Contains mitochondria which provides the energy for contraction

20

Root hair cell

Absorbs water and mineral salts from soil
Hair like structure to increase surface area to absorb more water/minerals

21

Sperm cell

Fertilises female gamete
Tail to swim
Mid section is full of mitochondria for energy to swim

22

Red blood cell

Absorbs oxygen and transports it around the body
No nucleus - more haemoglobin can be packed in, more space to carry oxygen
Biconave shape so it's flexible and fits through small capillaries

23

Ciliated cell (in oviduct)

Moves egg near uterus
Cilia on surface - beats regularly so egg moves down oviduct
Contains mitochondria for energy so cilia can move

24

Nerve cell (motor neurone)

Transmits nerve impulses
Contains fibres (dendrites) that connect to other neurones
Axon surrounded by myelin sheath to insulate and speed up transmission of nerve impulse

25

Diffusion

Movement of particles from a high area of concentration to a low area of concentration. No energy required

26

The greater the difference in concentration, the ... the rate of diffusion

Faster

27

Diffusion occurs in

Gases and liquids

28

Why can diffusion not occur in solids?

Particles are not free to move

29

Large surface area ... the rate of diffusion

Increases, more area is exposed so more diffusion can take place

30

Higher temperature ... the rate of diffusion

Increases, the hotter it is the more kinetic energy for diffusion

31

The stomach is an organ that contains

Muscular tissue
Glandular tissue
Epithelial tissue

32

Muscular tissue

Contracts for movement
Churn up contents

33

Glandular tissue

Produces hormones and enzymes
Produce digestive juices
Layer of cells
Make chemicals e.g. Acid
Lines inside of organs
Creates thick mucus to coat cells

34

Epithelial tissue

Cover outside and inside of stomach
Arranged evenly
Smooth allowing organs to easily move
Layers of cells
Protective coat around the organ

35

Tissues

Groups of similar cells that work to carry out a particular function

36

Organs

Groups of different tissues that work to perform a certain function

37

Organ systems

Group of organs working together to perform a function, organ systems form organisms

38

Digestive system - Salivary glands

Produces the enzyme amylase in saliva

39

Digestive system - Liver

Bile is produced
- neutralises stomach acid
- emulsified fats

40

Digestive system - Gall bladder

Where bile is stored before released into small intestine

41

Digestive system - Large intestine

Where excess water is absorbed from undigested foods, producing faeces

42

Digestive system - Small intestine

Where digested foods are absorbed and move into the blood
Produces amylase, lipase and protease to complete digestion

43

Digestive system - Rectum

Where faeces are stored, before leaving through the anus

44

Digestive system - Pancreas

Produces protease, amylase and lipase and releases them into the small intestine

45

Digestive system - Stomach

Pummels food with its muscular wall
Produces protease, amylase and lipase
Produces hydrochloric acid
- to kill bacteria
- give correct pH for protease enzymes to work (pH2 - acidic)

46

How are cone cells in the eye adapted to carry out its function?

-Outer segment of cell has a chemical called visual pigment - chemically changes in colour to allow you to see in colour
-The centre has lots of mitochondria, releases energy allowing visual pigment to reform
-Specialised nerve cell that transmits signals to brain so colour is continuously seen

47

How are fat cells adapted?

-small cytoplasm to allow space for fat to be stored
-few mitochondria as they do not use much energy
-can grow to 1000 times its original size

48

Tissues - examples?

Epithelial
Muscle
Blood
Bone

49

Organs - examples?

Stomach
Heart
Kidney
Lung
Skin
Small intestine

50

Organ systems - examples?

Brain
Circulatory
Digestive
Glandular
Nervous
Skeletal

51

Pancreas and salivary glands make digestive juices that

Lubricate food
Carry enzymes to aid digestion

52

Digestion

Breakdown of large food molecules into smaller particles that can pass through the gut wall and be absorbed into the blood

53

Absorption

Process by which smaller food particles are taken into the blood. They pass through the gut-wall into the blood from the gut environment

54

Plant organs contain

Stem
Roots
Leaves

55

Organ: stem

Supports the plant
Transports substances through the plant

56

Organ: leaf

Produces food by photosynthesis

57

Organ: roots

Anchors the plant
Takes in water/minerals from the soil

58

Leaf - upper epidermal tissue

Thin and transparent
Waxy cuticle
Allows light to pass to the mesophyll to protect the leaf and stop water loss

59

Leaf - palisade mesophyll

Regular shaped cells
Near upper surface
(Where most chloroplasts are found)
Absorbs the maximum amount of sunlight

60

Leaf - spongy mesophyll

Irregular shaped cells
Air spaces
Increases surface area for CO2 absorption to maximise
Allows gases to diffuse

61

Leaf - lower epidermal tissue

Surrounded by guard cells
Allows gases to diffuse
Guard cells open/close stomata

62

Leaf: vascular bundles

Contains xylem and phloem tubes
Transport substances from roots to the shoots and leaves

63

Leaf - guard cells

Opens and closes stoma to allow gas exchange

64

Why do plants need glucose?

-used in respiration to release energy
-joined together to make starch for storage
-combined with nutrients to make proteins for growth
-joined to make cellulose for cell walls
-converted to fats and oils for the seeds
-converted to fructose for the fruit

65

Photosynthesis equation

Carbon dioxide + water -> (light energy) -> oxygen + glucose

66

Limiting factors - photosynthesis

Light intensity
CO2
Temperature

67

What happens during photosynthesis?

Light energy is absorbed by chlorophyll (in chloroplasts)
The energy is used during by converting CO2 from the air and water from the soil into sugar (glucose)
Oxygen is a by product

68

Photosynthesis - light intensity

A shortage of light means less energy to power the reaction

69

Photosynthesis - temperature

A low temperature limits the rate of photosynthesis as molecules move slower so there are less reactions, however too high will cause enzymes to be denatured (40 degrees roughly)

70

Photosynthesis - CO2 concentration

This will limit the rate as there are less molecules in the reaction. A levelled off line on the graph shows it has reached its optimum point.

71

How can you grow plants in the ideal environment?

Grow then in a greenhouse as limiting factors can be controlled

72

Uses of glucose (from photosynthesis) in plants and algae

Converted into insoluble starch for storage
Used in respiration

73

Physical factors affecting organisms

Temperature
Availability of nutrients
Availability of light
Availability of water
Availability of oxygen
Availability of CO2

74

How temperature affects organisms

Affects the rate of an organisms metabolism
Some cannot tolerate extreme temperatures
Organisms with a high temperature may also struggle to tolerate extreme conditions

75

How availability of nutrients affects organisms

Nutrients e.g. Nitrate are essential for growth of plants/microorganisms
A low concentration would cause organisms to struggle to grow and survive

76

How availability of light affects an organism

Required as an energy source for photosynthesis
In low light intensities, plants grow very slowly

77

How availability of water affects organisms

All organisms require water
Chemical reactions take place in water solutions
An absence of water causes cells and in turn, organisms to die

78

How availability of oxygen affects organisms

Essential for aerobic respiration
May become limited in soil - so roots cannot grow and absorb the minerals/water
May become limited in water, so aquatic organisms struggle to respire

79

How availability of CO2 affects organisms

Essential for photosynthesis
Limited where there are many plants - reducing rate of growth

80

Water and CO2 are used to ... food during respiration

Synthesise

81

Phosphate - plants

For growth and respiration
Component of DNA
Deficiency symptom - discoloured leaf and poor growth

82

Magnesium - plants

Makes chlorophyll green
Deficiency symptom - chlorophyll goes yellow

83

Nitrate - plants

Found in water, creates amino acids which create proteins
Lack of nitrate - stunted growth

84

Potassium - plants

For photosynthesis and respiration
Must be present for respiration enzymes to work
Deficiency symptom - discoloured leaves and poor growth

85

Transect

A line across a habitat/ part of a habitat
The number of organisms of each species can be observed and recorded at regular intervals along the transect

86

Quadrat

Organisms underneath, usually plants, can be identified and counted

87

Why should quadrats be randomly placed?

So a representative sample is taken
The validity and reproducibility of the results increases as the results from more quadrats are analysed

88

Proteins

Made up of long chains of amino acids
Fold into a specific shape which dictates its function, another molecule will then fit into it

89

Uses of proteins in the body

Keratin in the hair/skin
Channels in cell membrane
Hormones
Haemogoblin in red blood cells
Antibodies
Collagen in blood vessel walls, skin, tendon and bones
Fibrin in blood clots (scabs)
Elastin in lungs/blood vessel walls

90

Catalysts

Substances that speed up reactions without being changed or used up

91

Biological catalysts

Enzymes, enzymes are proteins
Found in long chains
Speed up reactions
Specific (only catalyse a particular reaction)
Re-used

92

All proteins contain the elements

Carbon
Oxygen
Nitrogen
Hydrogen
Some sulphur

93

Reactions sped up by catalysts

Proteins
Respiration
Proteinsynthesis

94

You can change the shape of a protein by

Heating it
Changing its pH
Reacting it with chemicals e.g ethanol

95

What happens if a proteins shape changes?

It will not be able to carry out its function
It will be denatured

96

How does pH affect the active sight?

It effects the forces that hold the enzyme molecule together

97

What factors affect enzymes

pH
Temperature

98

Active sight

A specific shape that only a certain type of reactant (substrate) will fit into

99

How do enzymes affect activation energy?

It lowers the activation energy, so reactions occur at a greater rate
Particles do not need to collide with as much energy

100

How does temperate affect the rate of reaction with enzymes?

If it is too low, the rate of reaction falls as there is less kinetic energy
If it is higher, particles collide with more energy so the rate of reaction increases
If it is too high, the enzyme denatures and the active sight shape changes so the substrate can no longer bond. The rate of reaction falls

101

Digestive enzymes

Break down big molecules into smaller ones

102

Big molecules (digestion - examples)

Starch
Proteins
Fats

103

Small molecules (digestion - examples)

Sugars
Amino acids
Glycerol
Fatty acids

104

3 enzymes - digestive system

Amylase
Protease
Lipase

105

Amylase

Concerts starch into maltose and other sugars

106

Protease

Converts protein into amino acids

107

Lipase

Converts lipids into glycerol and fatty acids

108

Where is amylase made?

Salivary glands
Pancreas
Small intestine

109

Where is protease made?

Stomach (pepsin)
Pancreas
Small intestine

110

Where is lipase made in?

Pancreas
Small intestine

111

How does bile emulsify fats?

Breaks fats into tiny droplets
There is then a larger surface area of fat for lipase to work with so digestion is quicker

112

How does bile neutralise acid in the stomach?

The hydrochloric acid in the stomach makes the pH too acidic for enzymes to work
Bile is alkaline so it neutralises the acid

113

Where is bile stored and released into?

Stored in the call bladder
Released into small intestine

114

Biological washing powders

Contain enzymes (protease/lipase) to break down fats and proteins in stains

115

Enzymes must work well in solutions with a high pH because washing powders are

Highly alkaline

116

What is the range of temperatures enzymes must work at

10-90 degrees

117

When can enzymes be used in home and industry?

If microorganisms produce enzymes that pass out of the cells

118

Biological detergents are more effective at ... temperatures

Lower

119

Advantages of biological washing powders

Enzymes work at low temperature saving energy
More efficient at removing stains
Help delicate fabrics get cleaned without damaging then by a hot wash

120

Disadvantages of biological detergents

May lead to allergies and irritation
If clothes are not rinsed, the enzymes may remain in the clothing which would digest protein in the skin

121

Enzymes used in industry

Biological washing powders
'Pre-digested' baby foods
Diet foods/slimming products
Fruit juice

122

How does the function of enzymes affect confectionary/slimming products?

Breaks cheap starch into glucose
This changes to fructose syrup (by isomerase) so less of it if needs to get a sweeter taste

123

How does the function of enzymes affect baby food?

Protease 'pre-digests' the proteins so it is easier for the babies to eat and absorb into their blood

124

How does the function of enzymes affect fruit juice?

It makes it sweeter

125

How does the function of enzymes affect meat?

It tenderises and makes it softer

126

Properties of industrial enzymes

Long shelf life
Withstand high temperatures
Can work in the presence if chemicals that would otherwise stop enzymes working

127

Enzymes in the home

Used to break down food stains as biological detergents

128

Advantage of enzymes

Enzymes lower the temperatures and pressures often needed for chemical reactions
They are specific
Biodegradable

129

Disadvantages of enzymes

Sensitive to surroundings (changing pH or temperature may stop them working)
Expensive to control the conditions

130

Respiration

The process of releasing energy from glucose, which goes on in every cell

131

Aerobic respiration

glucose + oxygen -> carbon dioxide + water + energy

132

Aerobic respiration is respiration using...

Oxygen

133

Aerobic respiration occurs inside...

Mitochondria

134

The energy respiration releases is used to...

-Build larger molecules from smaller ones (proteins from amino acids)
-Allow muscles to contact in animals
-Allow birds/mammals to maintain a constant body temperature
-In plants to build up sugars, nitrates and nutrients into amino acids which are built into proteins

135

Cyanide

A toxin that stops respiration by stopping enzymes involved in the process from working

136

How can exercise affect us?

The depth and rate of breathing increases
Heart rate increases
Increases supply of blood flow to muscles of sugar/oxygen
Removal of CO2 increases

137

How is glycogen used during exercise?

Glucose from food can be stored as glycogen
Mainly stored in the liver but each muscle has its own store
During vigorous exercise, glucose can be converted back to glucose to provide further energy

138

Anaerobic respiration

Glucose -> lactic acid + (some) energy

139

Anaerobic respiration is respiration without

Oxygen

140

What is anaerobic respiration?

The incomplete breakdown of glucose into lactic acid. It does not release as much energy as aerobic respiration but is useful in emergencies

141

Lactic acid - anaerobic respiration

Lactic acids builds up in muscles, which is painful.
It tires out muscles- they stop contacting efficiently

142

What is oxidation?

Blood flows through the muscles to removed the lactic acid by oxidising it to CO2 and water

143

Every cell contains ... pairs of chromosomes

23

144

What is a gene?

A section of DNA

145

What is a chromosome?

Made up of DNA

146

What is a diploid number?

A full set (23 pairs of chromosomes)

147

Sex cells only have ... single chromosomes

23

148

What is mitosis?

Mitosis is when a cell reproduces itself by splitting to form two identical offspring

149

Mitosis makes new cells for...

Growth
Repair damaged tissue
Replace worn out tissue

150

DNA fingerprinting is used for...

Forensic science
Paternity testing

151

What do genes do?

They code for a specific protein
They tell cells the order for the amino acids

152

What is the exception to everyone having unique DNA?

Identical twins
Clones

153

Before cells divide in mitosis, what must happen?

The DNA must make a copy of itself

154

How does DNA make a copy of itself?

DNA is double stranded
The molecule unzips
This exposes DNA based
These bases then join to spare, complimentary bases
The bases then match to create an exact copy

155

Which DNA bases join together?

A - T
T - A
C - G
G - C

156

Mitosis is ... reproduction

Asexual, so there is no variation

157

How does the cell create an exact copy of itself in mitosis?

DNA replicates
The two duplicated chromosomes like up in the centre of the cell
Spindle fibres form
Each chromosome splits into two identical copies
Each copy moves to opposite ends of the cell
A membrane forms around each set
This becomes the nuclei
The cytoplasm then divides leaving two new cells that are identical

158

Meiosis

Produces cells which have half the number of chromosomes (gametes)

159

Where does meiosis occur and what does it result in?

It happens in sex organs and results in variation

160

Before meiosis occurs what should happen?

Before the cell divides, it duplicates its DNA

161

How does a cell create gametes through meiosis?

In the first division, chromosome pairs line up in the centre
The pair gets pulled into two separate cells as they are attracted to opposite poles (each cell has one copy of each chromosome)
In the second division, they line up again in the centre and split
You are left with four gametes each with a single set of chromosomes

162

Why does meiosis occur?

For sexual reproduction

163

What happens to gametes during fertilisation?

A single body cell with new pairs of chromosomes are formed
This cell then divides repeatedly by mitosis to develop into a new individual

164

What are stem cells?

Embryonic stem cells can turn into any type of cell

165

Where can stem cells be found?

Adult bone marrow
Human embryos

166

What is differentiation?

The process by which a cell changes to become specialised for its job

167

Are stem cells undifferentiated?

Yes

168

How can stem cells be used?

Nerve cells- helping those paralysed by spinal cord injuries
Beating heart muscle cells- those with heart disease
Insulin producing cells- those with diabetes

169

Arguments for stem cells

- those who are alive are more important than an embryo
- unwanted embryos from fertility clinics could be used instead
- medicine uses them to cure disease
- could replace faulty cells

170

Arguments against stem cells

- each embryo is a potential human life
- scientists should find other ways to obtain stem cells rather than using them from embryos

171

In asexual reproduction, the offspring contain the ... alleles as the parent

Same (they are genetically identical)

172

Why does variation occur in sexual reproduction?

When the gametes fuse, one of each pair comes from the parents

173

What determine the sex of the offspring?

One of the 23 pairs of chromosomes is different, and carries the gene that determines sex

174

Which chromosomes determine male characteristics?

All men have an X and a Y chromosome
The Y chromosomes causes the male characteristics

175

What chromosome determines the female characteristics?

All women have to X chromosomes
The combination of XX is what allows female characteristics to develop

176

What is an allele?

An allele is a version of a gene
E.g. The gene could be Hh and the alleles would be H and h

177

What is a dominant allele?

It controls the development of a characteristic when it is present in only one of the chromosomes

178

What is a recessive allele?

It controls the development of characteristics only if the dominant allele is not present

179

What is a genotype?

What alleles you have

180

What is a phenotype?

The characteristic displayed by the genotype

181

What is a heterozygous?

2 different alleles

182

What is a homozygous?

2 of the same alleles

183

Who worked out the main principles of inheritance?

Gregor Mendel

184

What 3 conclusions did Mendel reach?

-Characteristics in plants are determined by "hereditary units"
-Hereditary units are passed on from both parents (one unit from each parent)
-Hereditary units can be dominant or recessive - if an individual has both, the dominant characteristic will he expressed

185

What are hereditary units?

Genes

186

Why were Mendel's discoveries not recognised until after his death?

He published his work in an obscure journal
DNA, chromosomes and genes were not discovered yet
People couldn't accept the link between plants and animals
He was a monk, so wasn't as respected

187

What does DNA stand for?

Deoxyribose Nucleic Acid

188

How do genes control characteristics?

DNA forms a helix that protects it
Phosphate backbone
Bases

189

Why do the bases match together?

The shape of the molecule allows them to fit together

190

Chromosomes have ... folded DNA

Tightly

191

What are the four bases called?

Cytosine & Guanine
Adenine & Thymine

192

What is a triplet code?

Three bases joined with the opposite base

193

One triplet code creates an...

Amino acid

194

A chain of amino acids make a...

Protein

195

What forms the bond between bases?

A hydrogen bond

196

What is cystic fibrosis?

Genetic disorder of cell membranes
Body produces sticky mucus in air passages/ pancreas

197

Cystic fibrosis - explain the alleles

The allele that causes the disease is recessive 'f'
People with only one 'f' will not have the disorder (carriers)
To get the disorder, both parents must be carriers or sufferers
E.g. 1 in 4 chance if parents are both carriers
Only a sufferer if you have two 'f' alleles

198

What is Polydactyly?

Genetic disorder where baby's are born with extra fingers/toes
Not life threatening, little side effects

199

Polydactyly - explain the alleles?

Caused by the dominant allele 'D'
Can be inherited if one parent carries the defective allele
The parent with that allele will also suffer as the allele is dominant
E.g. 50% chance of child having disorder if one parents has the 'D' allele

200

What is embryo screening?

The screening of embryos to search if their alleles may cause a genetic disease m

201

Arguments for embryo screening

Stops people suffering
There are laws to stop it going too far
During IVF most embryos are destroyed anyways, this just allows the selected one to be healthy
Treating disorders is expensive

202

Arguments against embryo screening

People may use screening to pick their most desirable baby
Rejected embryos were potential human life
Screening is expensive
Implies those with disorders are 'undesirable' which increases prejudice

203

What is speciation?

The development of a new species

204

What 2 things lead to speciation?

Isolation
Natural selection

205

What is a species?

A group of similar organisms that reproduce to give birth the fertile offspring

206

Why does speciation occur?

When populations of the same species become so different they can no longer breed to produce fertile offspring

207

What is isolation?

When a population is levies is separated

208

What are the 4 stages of speciation?

Isolation - 2 species become separated
Genetic variation - they show variation because of the range of alleles
Natural selection - pass on characteristics to next generations
Speciation - populations become so different that interbreeding is no longer successful

209

Extinction happens if you can't ... quickly enough

Evolve

210

Reasons species become extinct

- new predators
- more competition
- catastrophic event e.g volcano
- diseases
- new species develops (speciation)
- change in environment

211

What are fossils?

The remains of plants and animals

212

3 ways fossils form in rock

-Gradual replacement by minerals (most common)
-Casts and impressions
-Preservation in places where no decay occurs

213

How does gradual replacement by minerals cause fossils to form?

Thing like bones do not decay easily
They get replaced by minerals as they decay and form a rock like substance shaped like the original bone/shells/teeth etc.
The surrounding sediment turns to rock but the fossil stays distinct in the rock

214

How do casts and impressions lead to fossils?

Fossils can form if the organism is buried in a soft material like clay
The clay hardens and the organism decays leaving a cast
E.g a plants roots can be preserved as casts
Things like footprints leave impressions in soft materials

215

How does preservation lead to fossils forming?

-In tar pits/ amber (clear yellow stone made from fossilised resin) there's no oxygen or moisture
Therefore decay microbes cannot survive
-In glaciers it's too cold for decay microbes to work
-Peat bogs are too acidic for decay microbes

216

Why can we not be sure on how life began?

Lack of valid and reliable evidence
This is because it's believed early organisms were soft bodied and decayed completely
Therefore the fossil record is incomplete
Geological activity may have destroyed fossils e.g tectonic plates moving