Biology Unit 1-5 (no 4) Flashcards

Question 1

Q

What is a species?

Answer

A

A species is a group of organisms that share common physical characteristicsMembers of the same species are capable of breeding together to produce viable offspring

Question 2

Q

What is evolution?

Answer

A

Evolution is the cumulative change in the heritable characteristics of a population

Question 3

Q

What happens in speciation?

Answer

A

Evolution can lead one species to diverge into two separate species. One species can gradually diverge into separate species by evolution

Question 4

Q

What do fossils tell us about evolution?

Answer

A

Fossils demonstrate gradual change in physical characteristics of a species - Fossils demonstrate species extinctionFossils record the gradual change in the characteristics of a species over long periods of time

Question 5

Q

What is a homologous structure?

Answer

A

A homologous structure is a physical characteristic shared by related species

Question 6

Q

What does the pentadactyl limb tell us about mammals?

Answer

A

All mammals are descended from a common ancestor The genetic code is universal. This provides evidence that all living species share common ancestors.

Question 7

Q

Outline the difference between artificial and natural selection.

Answer

A

Artificial selection:Organisms are selected for a purpose (better tasting food crops, smarter sheepdogs, faster racehorses)Artificial selection is carried out by humansNatural selection:Organisms are not selected for a purpose… instead the focus is on survivalNatural selection is driven by environment

Question 8

Q

How does artificial selection demonstrate evolution?

Answer

A

Selective breeding of domesticated animals (pets) shows this because they have evolved through human selection

Question 9

Q

What is a cline?

Answer

A

A cline is a gradation in one or more characteristics within a species.

Question 10

Q

Outline five types of evidence which support thetheory of evolution by natural selection

Answer

A

? fossils/paleontological: fossilized horse ancestors/other evidence? homologous structures: pentadactyl limb/vertebrate embryos/other? Selective breeding of domesticated animals shows that artificial selection can cause evolution? recent observed evolution: resistance to antibiotics/melanistic (dark color) insects in polluted areas/other recent example? geographic distribution: ring species/other evidence from geographical distribution? biochemistry: cytochrome c/other biochemical evidence

Question 11

Q

What explains similarities in structure when there are different function?

Answer

A

Evolution of homologous structures by adaptive radiation explains the similarity even when they have different functions.

Question 12

Q

What is adaptive radiation?

Answer

A

When organisms come from the same origin, like from an ancestor that had a pentadactyl limb, and they become different because they perform different functions.

Question 13

Q

What is a convergent evolution?

Answer

A

Organisms that have had different origins and have become similar because they perform the same or a similar function.

Question 14

Q

Give evidence from patterns of variation.

Answer

A

Example: human skin colour as evidence for evolution: • People with darker skin colour have evolved in places with high UV light –> protect them from cancer • People with lighter skin colour have evolved in places with low UV light –> helps them to generate enough Vitamin D

Question 15

Q

What is gradual divergence?

Answer

A

Continuous variation across the geographical range of related population matches the concept of gradual divergence.

Question 16

Q

Does the continuous range in variation match the belief that species were created as distinct types of organisms?

Answer

A

No it does not. Continuous range in variation is not constant or unchanging. It provides evidence for evolution and origin of species by evolution.

Question 17

Q

How did melanistic insects evolve?

Answer

A

Dark varieties of typically light coloured insects are called melanistic. The most famous example is the peppered moth which developed the melanistic variety in polluted industrial areas for better camouflage (change in natural environment)

Question 18

Q

Why do living organisms face a struggle for survival?

Answer

A

All species have great potential fertility2. Population sizes show long term stability3. Environmental resources are limitedLiving organisms have to compete with other members of their species in order to survive

Question 19

Q

Why do living organisms face a struggle for survival?

Answer

A

All species have great potential fertility2. Population sizes show long term stability3. Environmental resources are limitedLiving organisms have to compete with other members of their species in order to survive

Question 20

Q

What do members of a species show?

Answer

A

Living organisms show an enormous range of variation. No two living organisms are ever truly identical, even if they are genetic clones

Question 21

Q

Only under what condition can natural selection occur?

Answer

A

Natural selection can only occur if there is variation among members of the same species.Adaptations are characteristics that make an individual more suited to survive in its environment and successfully reproduce.

Question 22

Q

What promotes genetic variation?

Answer

A

Independent assortment, Meiosis, Gene Mutation and sexual reproduction

Question 23

Q

How does natural selection lead to evolution?

Answer

A

Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring2. individuals that reproduce pass on characteristics to their offspring3. natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species

Question 24

Q

Explain how the use of antibiotics has led to the evolution of resistant bacteria

Answer

A

members of a population of the same species show variation- some organisms are more likely to survive due to selective advantage- these variations may be genetically controlled/heritable- these genes are most liekly to be passed on to offspring - this can change the characteristic of the population- bacteria can noramlly be killed by antibiotics- anti biotics impose a selection pressure - if few bacteria have natural resistance to the antibioticthey will survive- if the resistance is heritable they will pass it on their offspring- they will reproduce/evolve to form bacterial colonies resistant to antibiotics.

Question 25

Q

Explain how the use of antibiotics has led to the evolution of resistant bacteria

Answer

A

members of a population of the same species show variation- some organisms are more likely to survive due to selective advantage- these variations may be genetically controlled/heritable- these genes are most liekly to be passed on to offspring - this can change the characteristic of the population- bacteria can noramlly be killed by antibiotics- anti biotics impose a selection pressure - if few bacteria have natural resistance to the antibioticthey will survive- if the resistance is heritable they will pass it on their offspring- they will reproduce/evolve to form bacterial colonies resistant to antibiotics.

Question 26

Q

Briefly explain Darwin`s theory of evolution.

Answer

A

• Species tend to produce more offspring than the environment can support• the consequence of the potential overproduction of offspring is a struggle for survival• Mutation, meiosis and sexual reproduction cause variation (different characteristics) between individuals in a species.• Adaptations are characteristics that make an individual suited to its environment.• Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring.• Individuals that reproduce will pass on characteristics to their offspring.• This selective “pass on characteristics” is called natural selection.• Natural selection leads to change in allele frequency.• Characteristics acquired during the lifetime of an individual (Eg. Learned skills) are not heritable. Therefore, it does not affect evolution.

Question 27

Q

What is an acquired characteristic?

Answer

A

An Acquired characteristic is a change that happens to an organism during its lifetime. These types of characteristics do not affect DNA and are not heritable.

Question 28

Q

Discuss evidence against the theory of evolution by inheritance of acquired characteristics.

Answer

A

? This is an incorrect theory stating that characteristics acquired during the lifetime of an individual can be passed on to next generation.? Acquired characteristics example: giraffes reach for leaves on tall tree, therefore their neck becomes longer, over many generations, giraffes have long neck.? This theory is incorrect because it relies on phenotypic inheritance, not genotypic inheritance /somatic changes cannot be passed on? example: if tail cut off rat – offspring still have tails? cannot be repeated experimentally since very many generations would be necessary? also mutations would have to be eliminated in such anexperiment – impossible

Question 29

Q

Explain with an example of natural selection causes progressive change.

Answer

A

Darwin collected finches which varied in sizes and shapes of their beaks.Beaks characters and diet are closely related, when one changes the other does also. Medium ground finch can eat large and small seeds whereas small finch can only eat small seeds.Daphne Major absence of small ground finch so… When eating small seeds the medium ground finch was smaller in body and beak size. When there was a shortage, the larger beaked individuals survived.Variation in beak and body size is mostly due to genes but the environment has some effect. The proprtion of the variation due to genes is called heritability.

Question 30

Q

What is progressive change?

Answer

A

Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics.

Question 31

Q

What is adaption?

Answer

A

Adaption are characteristics that make an individual suited to its environment.

Question 32

Q

What are organisms classified into?

Answer

A

All organisms are classified into three domains. (Archaea, eubacteria and eukaryote should be used for the three domains. Members of these domains should be referred to as archaeans, bacteria and eukaryotes)

Question 33

Q

Why are viruses not classified as living organisms?

Answer

A

They are acellular: viruses are not composed of cells
They have no metabolism: metabolism is the sum total of all biochemical reactions that occur inside cells… without cells viruses have no metabolism
They are unable to reproduce independently viruses must inject their genetic material into a host cell in order to replicate themselves

Question 34

Q

How do taxonomist classify species?

Answer

A

They use the hierarchy of taxa.

Question 35

Q

What are the principal taxa for classifying eukaryotes?

Answer

A

Kingdom, Phylum, Class, Order, Family, Genus, SpeciesKing Phillip Came Over For Good Spaghetti

Question 36

Q

Classify one animal species from domain to species level.

Answer

A

LionKingdom: AnimaliaPhylum: ChordataClass: MammaliaOrder: CarnivoraFamily: FelidaeGenus: PantheraSpecies: leo

Question 37

Q

Classify one plant species from domain to species level.

Answer

A

Dog RoseKingdom: PlantaePhylum: AngiospermsClass: EudicotOrder: RosalesFamily: RosaceaeGenus: RosaSpecies: canina

Question 38

Q

Why do we use the system of binomial nomenclature for naming?

Answer

A

Universal system helps international collaboration - Names are descriptive (is Latin)- The bionomial system allows us to identify species that are closely related (i.e. Rattus norvegicus and Rattus rattus)

Question 39

Q

Which plant phyla has vascular tissues?

Answer

A

Filicinophyta

Question 40

Q

What are four plant phyla? (give example)

Answer

A

Bryophyta - mossesFilicinophyta - fernsConiferophyta - conifersAngiospermophyta - flowering plants

Question 41

Q

What characteristics identify Bryophyta?

Answer

A

have no roots
have simples leaves/stems
produce spores in capsule
are nonvascular - exhibit alternation of generations/ is a significant gametophyte generation

Question 42

Q

What characteristics identify Filicinophyta?

Answer

A

have roots, stems and leaves
(often) have divided/pinnate leaves
produce spores in sporangia/ spores on undersides of the leaves
exhibit alternation of generations - have primitive vascular tissues

Question 43

Q

What characteristics identify Coniferophyta?

Answer

A

have woody stems
(often) have narrow leaves/needles/scales
produce seeds in cones/ unenclosed seeds

Question 44

Q

What characteristics identify Angiospermophyta?

Answer

A

have flowers - have ovules in ovaries - produce seeds (with hard coats) in fruits

Question 45

Q

What are the different phyla for animals?

Answer

A

Porifera, Cnidaria, Platyhelminthes, Annelida, Mollusca, Arthropoda

Question 46

Q

What characteristics identify Porifera?

Answer

A

• No clear symmetry• Attach to a surface under water• Pores (holes) extend through the body• No mouth or anus

Question 47

Q

What characteristics identify Cnidaria

Answer

A

• Radial symmetry• Tentacles sometimes with stinging cells• Mouth but no anus (pocket gut)

Question 48

Q

What characteristics identify Platyhelminthes?

Answer

A

• Bilateral symmetry• Flat body• No segmentation• mouth but no anus (pocket gut)

Question 49

Q

What characteristics identify Annelida?

Answer

A

• Bilateral symmetry• Often have bristles• Clear segmentation• Mouth and anus present (tube gut)

Question 50

Q

What characteristics identify Mollusca?

Answer

A

• Muscular foot or mantle• Usually have a shell (not squid or octopus)• No visible segmentation• Mouth and anus are present (tube gut)

Question 51

Q

What characteristics identify arthropoda?

Answer

A

• Bilateral symmetry• Hard exoskeleton• Clear segmentation and jointed appendages (arms, legs, feelers, claws)

Question 52

Q

What are the classes of the phylumof chordata?

Answer

A

Birds, Mammels, Amiphibians, Reptiles, Fish

Question 53

Q

What are external recognition of birds?

Answer

A

A bird is an animal with feathers.
Birds have two legs and two wings.
Birds have a beak or a bill.
They lay eggs on land
They are warm-blooded

Question 54

Q

What are physical characteristics of mammels?

Answer

A

They have fur or hair.
The babies drink milk from their mother’s bodies.
They have four limbs (arms, legs, flippers).
They are warm-blooded.
Most mammals are born alive.
They breathe air through lungs.

Question 55

Q

What are physical characteristics of amphibians?

Answer

A

Cold blooded
Live both under water and on land (live in damp places)
Lay jelly covered eggs in water
Breath with gills (babies)
Moist skin

Question 56

Q

What are physical characteristics of reptiles?

Answer

A

They have dry, scaly skin.
They have short legs or no legs at all.
They breathe with lungs.
They are cold-blooded.
Most young reptiles hatch from eggs on land

Question 57

Q

What are physical characteristics of fish?

Answer

A

Fish are cold blooded.
Fish lay eggs.
Most fish are covered with scales
They have fins not legs.
Fish live in water and breathe through gills.

Question 58

Q

Distinguish between the 3 domains of classification

Answer

A

Bacteria (exp: E.Coli)
* Prokaryote = no nucleus Cells walls contain peptidoglycan NO Histone proteins NO introns
Archae (Exp: Halobacteria)
* Prokaryote = no nucleus Cells walls do not contain peptidoglycan Histone proteins bound to DNA Some genes contain introns
Eukaryotes (Exp:Saccharomyces)
* DNA inside a nuclear envelope = Eukaryote Histone proteins Genes contain introns frequently Cell wallsnotmade of peptidolgycan

Question 59

Q

What does a natural classification include?

Answer

A

In a natural classification, each taxon includes all of the organisms that descended from one common ancestor

Question 60

Q

What does an artificial classification include?

Answer

A

In a artificial classification, the taxa do not include of descended from one common ancestor.

Question 61

Q

Outline two advantages of natural classification

Answer

A

It allows us to make predictions about living species, based on what we know about other closely related organisms
It helps us to find characteristics to identify a species

Question 62

Q

What happens when taxonismist find new evidence?

Answer

A

Taxonomists sometimes reclassify groups of species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species

Question 63

Q

What is a clade?

Answer

A

A group of organism that includes all of the evolutionary descendants of a common ancestor

Question 64

Q

What is a cladogram?

Answer

A

A tree diagram that shows the most probable sequence of divergences in a clade

Answer 65

A

No reptiles are not a clade because they do not include all descendant of a common ancestor.

Answer 66

A

Evidence for which species are part of a clade can be obtained form the base sequence of a gene or the corresponding amini acid sequence.

Answer 67

A

Sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species.Changes in the DNA base sequence for a specific gene expected to occur gradually, at a constant rate

Answer 68

A

An analogous trait is a characteristic that two organisms share due to convergent evolution, not common ancestry

Answer 69

A

A homologous trait is a characteristic that two organisms share due to common ancestry

Answer 70

A

Evidence from claditics has shown that classifications of some groups based on structure did not corespond with the evolutionairy origins of a group of species

Answer 71

A

Falsification of theories with one theory being susperseded by another plant families have been reclassified as a result of evidence from cladistics.

Answer 72

A

Figwort family isan example of a plant taxon that has been reclassified in light of new evidence from DNA analysis and cladistics

Answer 73

A

Giant algae (mermaid’s wineglass) The entire organism is made from only 1 cell that can reach to 7cm. The orgasm is not divided into smaller cells. Aseptate fungusMany fungi are aseptate, this means that the cell walls that divide the cells have broken down. The cytoplasm is continuous with many nuclei. Skeletal musclesCells fuse together to form muscles fibers. It is impossible to tell where one cell ends and next begins. Slime mold They reproduce when many cells fuse together to form a multi nucleate jelly.

Answer 74

A

(image size)/(actual size)=magnification

Answer 75

A

All living organisms are made of cells2. A single cell is the smallest unit of life3. Cells come from the division of pre-existing cells.

Answer 76

A

7-8 micrometers

Answer 77

A

30 micrometers

Answer 78

A

50 micrometers

Answer 79

A

1000 micrometers

Answer 80

A

1000 micrometers

Answer 81

A

10,000 micrometers

Answer 82

A

2,000 micrometers = 2,000,000 nm

Answer 83

A

800 micrometers

Answer 84

A

23,400 micrometers

Answer 85

A

23,400 micrometers

Answer 86

A

Nutrition, metabolism, growth, response, excretion, homeostasis, reproduction.

Answer 87

A

All organisms are sustained by chemical reactions that take place inside their cells, including respiration to release energy.

Answer 88

A

Keeping conditions inside the organism within tolerable limits. (Release Sweat and shiver)

Answer 89

A

Heat production increases.

Answer 90

A

The production of waste products increase.

Answer 91

A

The usage of nutrients and oxygen increases as it demands more.

Answer 92

A

The surface area to volume ratio decreases as volume increases.

Answer 93

A

As the volume increases, heat production significantly increases while surface area is not enough to balance heat loss, causing the cell to overheat. 2. As volume increases waste production increases while the surface area to volume ratio decreases, waste excretion is harder. 3. As volume increases, resource consumption directly increases, while resource absorption does not increase as much, causing a limitation towards absorption.

Answer 94

A

In the small intestine, microvilli increase surface area.2. Plant roots increase surface area for absorption of nutrients. 3. Red blood cells have a donut shape which increase surface area.

Answer 95

A

Emergent properties arise from the interation of compnent parts: the whole is greater than the sum of of its parts

Answer 96

A

Different cells are dedicated to carrying out different functions. Specilized cells have their own structures to enable them to perform their roles

Answer 97

A

Is responsible for carrying out electrical signals over long distance

Answer 98

A

Thye are responsible for the transportation of oxygen.

Answer 99

A

Stem cells are theprimarycells that areundifferentiatedHave the capacity to differentiate themselves

Answer 100

A

When cell differentiate, they become specialized cells.To become speialized cells, they turn off unnecessary genes

Answer 101

A

The capacity of stem cells to divide and differenciate along different pathways.This makes them suitable for treatments.

Answer 102

A

Heart failureheart muscles are usually damaged so adult stem cells can be used to replce in order to repair damamged heart muscles.Umbiblical Stem cellFaconi anaemia is a blood disease that can be treated using umbiblical stem cells.

Answer 103

A

A prokaryote is a cell without a nucleus. All bacteria are prokaryotic.

Answer 104

A

Cell wallPlasma MembraneFlagellum PiliCytoplasm RibosomesNucleoid DNA

Answer 105

A

Provides support and keeps the cell in the right shape and protects the cell from outside damage.

Answer 106

A

Enables the cell to stick other surfaces, or other bacterial cells.

Answer 107

A

It is a “propeller” that enables the cell to move.

Answer 108

A

The plasma membrane regulates the movement of materials in and out of the cell.

Answer 109

A

Most made out of water. the place where most chemical reactions take place.

Answer 110

A

Produces protein. Free ribosomes in prokaryotes are size 70S while eukaryotes are 80S

Answer 111

A

A nucleoid only applies for prokaryotes. It’s a region where the naked DNA is located

Answer 112

A

Prokaryotes multiply through binary fission.

Answer 113

A

The DNA duplicates itself in the cellThen the cell elongatesFinally, the cell will split into two new cells.

Answer 114

A

RibosomesNucleusGolgi apparatusMitochondriaCytoplasmRough endoplasmic reticulumPlasma membraneVesiclesLysosomesVacuole

Answer 115

A

RibosomesCell wallNucleusGolgi apparatusMitochondriaCytoplasmRough endoplasmic reticulumPlasma membraneVesiclesLysosomesVacuole

Answer 116

A

Eukaryotes are compartmentalized while prokaryotes are not. Prokaryotes do not have a nucleus while eukaryotes have a nucleus protecting their DNA

Answer 117

A

It’s the site for aerobic respiration. This means that converts and so produces energy.

Answer 118

A

They involve the the processing and packaging of protein molecules which are using the vesicles send outside the cell.

Answer 119

A

The RER produces protein that is then sent to the golgi apparatus.

Answer 120

A

small membrane bound sack containing biological molecules that can transport from the cell

Answer 121

A

Small membrane bound sack containing digestive enzymes.

Answer 122

A

Vacuoles are large membrane bound sacks used for storage ie. waste, sugar, salt, water

Answer 123

A

Many mitochondria indicate that the cell is in high demand for energy. It is a very active cell.

Answer 124

A

The cell is doing lots of photosynthesis.

Answer 125

A

Lots of RER indicates the cell is producing lots of protein to be exported.

Answer 126

A

Eukaryoteshave a nucleus which protects the DNA mixed with protein.Prokaryotesdo not have a nucleus. Their naked DNA is located in the nucleoid.
Eukaryotesare compartmentalized.Prokaryotesare not compartmentalized.
Eukaryoteshave mitochondria.Prokaryotesdo not have mitochondria.
Eurkaryoticribosomes are 80S.Prokaryoticribosomes are 70S
Eukaryotesdonothaveaflagellum.Prokaryoteshave a flagellum.
Eukaryotes do not have pili.Prokaryoteshave pili.
List similarities as well

Answer 127

A

Plantcells have chloroplasts.Animal cellsdo not have chloroplasts.
Plantcells have cell walls. Animalcells can change shape as they do not have cell walls.
Plantcells have large, central vacuoles.Animalcells only sometimes have vacuoles. If they do, they are smaller and temporary.
List similarities.

Answer 128

A

They have higher resolution due to technology.

Answer 129

A

Hydrophilic heads (phosphate group, glycol) and Hydrophobic tails (2 fatty acids)

Answer 130

A

Amphipathic means that the organism is partly hydrophilic as well hydrophobic, like a phospholipid.

Answer 131

A

The hydrophilic heads are pointed outwards. They are attracted to the water inside and outside of the cell. The hydrophobic tails are pointed inwards as they avoid contact with the water. They are also attracted to each other. The nature of amphipathic nature of phospholipids helps to ensure stability of the plasma membrane.

Answer 132

A

In their model, the phospholipid layer is sandwiched by two layers of protein as they know that they contain protein due to the evidence of membranes being isolated from red blood cells contain protein. This as well as the fact that the surface of an actual biological membrane is more wettable than an artificial, lead them to think that membranes are coated by protein which absorb the water.

Answer 133

A

A membrane with an outside layer of protein would not be stable as it block the absorbance of water for the hydrophilic part of the phospholipid. Membrane proteins can change their positions within the lipid layer.So, the new model showed that Proteins are individually embedded in the lipid layer. This lets the hydrophilic portions expose to its maximum to water which keeps the layer stable.

Answer 134

A

Phospholipid bilayer (hydrophilic head & hydrophobic tails)
Cholesterol
Glycoprotein
Integral proteins
Peripheral proteins.

Answer 135

A

Cholesterols are part of animal membranes. They make the layer less fluid.

Answer 136

A

An integral protein.

Answer 137

A

a peripheral protein

Answer 138

A

Diffusion is a passive movement of particles from a region of high concentration to low concentration.

Answer 139

A

There are two types of diffusion. simplified and facilitated. There is also active transport and osmosis. There is also exocytosis and endocytosis.

Answer 140

A

Diffusion does not require energy. Active Transport goes against the concentration gradient while Diffusion goes down the concentration gradient.

Answer 141

A

Both do not require energySimplified diffusion does not require protein channels. Facilitated diffusion required protein channels. In both diffusions, substances move down a concentration gradient.

Answer 142

A

This is the movement of substances against the concentration gradient. This means it goes from a region of low concentration to high concentration. Unlike passive transportations, this requires energy. Protein pumps are also needed for active transportation. .

Answer 143

A

Osmosis is the movement of water through a semipermeable membrane, from a region of high water concentration to a region of low water concentrationOsmosis does not require energy. It is an example of passive transportation.

Answer 144

A

In order to use tissues or organs in medical procedure, the organs must be bathed in a solution of the same osmolarity as the cytoplasm of the cell in order to prevent osmosis.

Answer 145

A

The point where the line crosses the X axis, gives us an estimate of the concentration of the cytoplasm of the potato cells. We can also see that at 0.16mol/dm3 the size of the potato chip should not change.

Answer 146

A

Due to the fluidity of the plasma membrane, the membrane can change its shape, break and re-form during endocytosis or exocytosis. Both membrane transportations require energy.

Answer 147

A

Endocytosis works through the change of shape of the membrane. The membrane will sink inwardly, forming a pit which encloses the material coming into the cell. The the membrane seals back on itself as the edges fuse. This vesicle then will break away from the membrane and move into the cytoplasm. The particles have now entered the cell enclosed by a vesicle.

Answer 148

A

In both exocytosis and endocytosis, vesicles are used to transport materials that are too large to enter the cell through passive or active transport. In exocytosis, protein produced in the RER is send to the golgi apparatus via vesicles which are then packaged and processed to be send via vesicles to the plasma membrane. The vesicle attaches itself to the membrane and fusion to the membrane releases the material inside the vesicle.

Answer 149

A

The spontaneous cell theory, proposed that cells just spontaneously appear. Yet, Pasteur’s experiment proved that bacteria could only come from other bacteria. This means that cells can only come from preexisting cells.

Answer 150

A

The first cell is an exception to Pasteur’s theory as the first cell is an emergent property of non living chemicals.

Answer 151

A

No, this can no longer happen today because our environment has become to sterile. This means that even if the chemicals existed, they would probably be eaten by some of our bacteria today.

Answer 152

A

The theory holds that mitochondria and chloroplasts started out as living bacteria inside of a eukaryote. As the relationship benefited both, it became permanent.

Answer 153

A

Mitochondria has its own DNA. Mitochondria has 70S ribosomes like prokaryotes. They are about the same size as prokaryotes.They reproduce through a similar process of binary fission.

Answer 154

A

embryonic development2. repair3. growth4. asexual reproduction

Answer 155

A

Mitosis Prophase The nuclear is broken down. The DNA condenses to be visible chromosomes through supercoiling. Spindle fibers grow from each of centriolesMetaphase The chromosomes line up at the equator. The spindle fibers attach themselves to each chromatid.Anaphase The spindle fibers shorten as the chromatids are now pulled apart into sister chromatids.Telophase Chromosomes uncoil. The 2 nuclear membranes form around each pole. Spindle fibers break down.Interface

Answer 156

A

Interphase is a very active part of the cell cycle. In this part, many processes occur in the nuclear and cytoplasm.

Answer 157

A

Interphase

Answer 158

A

Metaphase

Answer 159

A

Telophase

Answer 160

A

Cytokinesis

Answer 161

A

Mitotic index = (total number of cells doing mitosis)/(total number of cells)

Answer 162

A

Mitotic index is often used for doctors to determine whether the patient has cancer, as well as the chance of the patient’s survival, and whether or not the patient will respond positively or negatively to chemotherapy.

Answer 163

A

Animal cells do not have cell walls. Plant cells have cell walls that is created through a cell plate. Vesicles do not line up in an Animal Cell.Vesicles line up along the equator in Plant cells. Animal cells are separated by cleavage furrow. Plant cells are not separated by cleavage furrow. List similaritieseg. Both plant and animal cells’ cytoplasm is separated.Both plant and animal cells form 2 genetically identical daughter nuclei.

Answer 164

A

Cyclins are proteins that control the progression of cells through the cell cycle by activating enzymes.

Answer 165

A

Mutagens:physical or chemical factor that causes DNA mutations physical (UV, Xray, gamma radiation) Chemical (polonium,carbon monoxide, radium)
Oncogenes:genes that have the potential to cause cancer. Usually have rapid growthMetastasis:when cancerous cells break off from a tumour, they travel in the body stream, and cause new tumours elsewhere.

Answer 166

A

Tumour presents an example of an uncontrolled cell division.

Answer 167

A

Water is made out of the covalent bondings of two positive hydrogen atoms and one negative oxygen atom.

Answer 168

A

It is the bond between different water molecules. This is due to the fact that the water molecule has polar charged regions that attract itself to other water molecules’ polar regions.

Answer 169

A

Thermal properties of water include heat capacity, boiling and freezing point.

Answer 170

A

Water has a high heat capacity meaning that it takes much more energy to increase change its temperature than, say methane.

Answer 171

A

Water has a high heat capacity due to its strong hydrogen bonds that make it difficult for them to break without sufficient energy. This means that water remains relatively stable. This property is often used for animals as they can cool themselves or warm themselves in the water.

Answer 172

A

Due to water’s high latent heat capacity, it takes water molecules much more energy to convert from liquid to gas. This means that because of the strong hydrogen bonds, they require a lot of energy to break apart in order for water to evaporate.

Answer 173

A

Sweat is released in order cool the body down, as the sweat evaporate, leaving the surface of the skin cooler as all the high energy (hot) molecules are released into the atmosphere. In a humid climate, the air already contains lots of water which means that there is not enough space for the sweat to evaporate, leaving the body hot and drenched.

Answer 174

A

The high boiling point enables organisms to survive in hotter climates. If water did not have such high specific heat capacity, organisms would boil along the water and be unable to survive.

Answer 175

A

When water freezes, it becomes less dense. This means that the ice blocks will float atop of the water. Ice covered surface on lakes and seas acts as an insulator for the water underneath to maintain habitats for organisms.

Answer 176

A

One of the properties water has is its cohesion. Due to the hydrogen bonds, water is able to be transported from the roots to leaves through long columns.

Answer 177

A

When sugar is mixed into water, it dissolves presenting water’s solvent properties because of its polarity.

Answer 178

A

Oxygen has low solubility in water and therefore needs to be transported through haemoglobins.

Answer 179

A

Glucose, amino acids and sodium chloride are soluble.

Answer 180

A

Molecules like fats and cholesterol have low solubility, and need to be transported inside lipoproteins in blood.

Answer 181

A

CHO - Carbon, Hydrogen, Oxygen

Answer 182

A

CHON - Amino acid: Carbon, Hydrogen, Oxygen and Nitrogen

Answer 183

A

CHO - Carbon, Hydrogen, Oxygen

Answer 184

A

CHOP - Carbon, Hydrogen, Oxygen, Phosphate

Answer 185

A

Mineral compounds such as salts, i.e. sodium chloride, potassium sulphate, ammonium nitrate, etc.

Answer 186

A

Carbon based molecules found in living organisms.

Answer 187

A

These carbon based molecules are found in living organisms but are considered inorganic:Carbon MonoxideCarbon DioxideCarbonatesHydrogen Carbonates

Answer 188

A

Friedrich Wöhler has proven that you can artificially make urea in laboratory. As Urea is an organic matter, you can produce organic matter with inorganic matter without vital force.

Answer 189

A

Ribose is a pentose sugar. It is a monosaccharide.

Answer 190

A

Glucose is a hexose sugar. It is a monosaccharide.

Answer 191

A

Glucose is a hexose sugar. It is a monosaccharide.

Answer 192

A

Sucrose is disaccharide of glucose and fructose.

Answer 193

A

Pentose is a sugar made of 5 carbon atoms while a hexose sugar has 6 carbon atoms

Answer 194

A

Sucrose, Maltose, Lactose

Answer 195

A

A Polysaccharide is a carbohydrate of a chain of many sugars which are for example starch or cellulose.

Answer 196

A

Glycosidic bond is formed between sugar molecules.

Answer 197

A

Each amino acid contains: R group, carboxylic acid group, amino group, hydrogen atom and carbon atom in the middle.

Answer 198

A

Two amino acids bond to form a dipeptide. Amino acids join together through peptide bonds. This is a condensation reaction meaning it forms water as a by product.

Answer 199

A

carbohydrates are organic compounds that contain one or more simple sugars.

Answer 200

A

Large organic compounds made of a polypeptide of amino acids arranged in a linear shape.

Answer 201

A

Saturated lipids are linear, meaning they have no double carbon-carbon bonds.

Answer 202

A

Triglycerides, phospholipids and steroids.

Answer 203

A

This is triglyceride which is a lipid.

Answer 204

A

This is a phospholipid which is a lipid.

Answer 205

A

This is a steroid which is a lipid.

Answer 206

A

Lipids are used for electrical insulation, energy storage, plasma membrane (phospholipid and cholesterol) and thermal insulation.

Answer 207

A

Lipids a good electrical insulators as they do not conduct electricity.

Answer 208

A

Metabolism are the chemical reactions within the cell in its cytoplasm. It is the enzyme-catalyzed reactions in living organism.

Answer 209

A

Anabolism is the synthesis of small, simple molecules forming a complex compound. This includes the formation of macromolecules from monomers by condensation reaction.

Answer 210

A

Catabolism is the breakdown of complex compounds to small simple molecules. This includes the hydrolysis of macromolecules into monomers.

Answer 211

A

Maltose is disaccharide created through the condensation of two alpha glucose which are bonded through a glycosidic bond.

Answer 212

A

Sucrose is a disaccharide formed through two monosaccharides, glucose and fructose.

Answer 213

A

Lactose is a disaccharide formed through two monosaccharides, galactose and glucose.

Answer 214

A

Maltose is formed through two alpha glucose.

Answer 215

A

Starch is polysaccharide of alpha glucose which comes in the form of amylose and amylopectin together.

Answer 216

A

Amylose is a chain of alpha glucose bonds which is spiralled.

Answer 217

A

Amylopectin is similarly to amylose made of alpha glucose but it branched.

Answer 218

A

Cellulose is polysaccharide made of a chain of beta glucose. It serves as a material to form plant cell walls.

Answer 219

A

Glycogen is very similar to amylopectin and is therefore made of alpha glucose. It is more branched. It serves as an energy source in human liver and muscles.

Answer 220

A

Unsaturated fatty acids have double carbon-carbon bonds. This makes them bend.

Answer 221

A

Monounsaturated fatty acids only have one double carbon-carbon bond. Polyunsaturated fatty acids have 2 or more double carbon-carbon bonds.

Answer 222

A

Cis and trans are structures of unsaturated fatty acids.

Answer 223

A

Cis resembles a C meaning that it curves back.

Answer 224

A

Trans is a nonpolar molecule, this makes the fatty acid a kink but stay relatively linear

Answer 225

A

Triglyceride is formed through 3 fatty acids and a glycerol. The fatty acids attach themselves through condensation reaction which gives water as a byproduct

Answer 226

A

Measure your mass with a scale in kg2.Measure your height with a tape in meters 3. Divide your mass by your height squared=> BMI = weight/ (height)^2

Answer 227

A

Lipidsare more suitable for long term energy storage.Carbohydratesare more suitable for short term energy storage.
Lipidsrelease double the amount of energy with the same amount of gramsascarbohydrates.Carbohydratesrelease much less energy copared to lipids.
Lipidsare stored in specialized cells such as triglycerides in adipose.Carbohydratesare stored in muscle tissues and the liver. This makes lipids more readily stored than carbohydrates.
Lipidstake longer to break down.Glycogenis easier and faster to break down into glucose.

Answer 228

A

There is a high correlation that a high intake of trans fats and saturated fatty acids. This is due to the fact that trans fats and saturated fatty acids can stack on each other and clot up blood vessels.

Answer 229

A

Biological proteins are made up of 20 different types of amino acids.

Answer 230

A

Amino acids can be found through our diet and nutrients. Some amino acids can also be synthesized by human cells.

Answer 231

A

Whether amino acids are polar or nonpolar depends on their variable group (R group).Polar makes them hydrophilic.Non Polar makes them hydrophobic.

Answer 232

A

The outer layer of an enzyme contains polar (hydrophilic) amino acids. This helps to make the enzyme soluble.

Answer 233

A

The inner pore of a membrane channel will contain polar amino acids, while the amino acids in contact with the lipid bilayer will be nonpolar. This keeps the protein from floating away.

Answer 234

A

The inner layer of proteins will contain many non polar amino acids that help to stabilize the shape of a soluble protein.

Answer 235

A

Most organisms have proteins that consist of the same 20 amino acids.There are a few exceptions that are likely to come from distant evolutionary relatives.

Answer 236

A

Amino acids link through condensation reaction, forming a peptide bond to make a dipeptide or polypeptide.

Answer 237

A

In cells, amino acids are joined by free ribosomes or by ribosomes attached to the RER.

Answer 238

A

The sequence of amino acids in polypeptides are codes for the genes.

Answer 239

A

Primary structure is a sequence of amino acids. The moleculeis called a polypeptide.

Answer 240

A

Secondary structure is the folding of the polypeptide to a combination of spiralled alpha helices and pleated beta sheets. They are held together by hydrogen bonds.

Answer 241

A

Tertiary structure is the chain folding into a specific 3D structure. The structure is held together by a number of different kinds of bonds.

Answer 242

A

A quaternary structure does not always occur.This occurs when two or more proteins in tertiary structure are bonded together to make 1 molecule.

Answer 243

A

To form a conjugated protein, the quaternary structure involves the binding of a prosthetic group.

Answer 244

A

Fibrous proteins such as keratin which is found in hair is linear. While globular proteins such as pepsin are round.Fibrous proteins such are Keratin are insoluble. Other, globular proteins such as pepsin are soluble in waterFibrous proteins are less sensitive to changes in temperature and pH. Globular proteins are more sensitive.Fibrous proteins perform structural roles. Globular proteins act as catalysts.

Answer 245

A

Proteome is the sum of all the proteins in one biological individual. This differs and is unique for every individual as we do not make the same amount of proteins.

Answer 246

A

Rubisco is the enzyme that catalyzes carbon fixation in green plants. This is a key event in photosynthesis.

Answer 247

A

Insulin is hormone involved in the regulation of blood glucose concentration. It is composed of 2 peptides chains and totalling 51 amino acids.

Answer 248

A

Immunoglobulins act as antibodies which are large Y-shaped proteins that are used by the immune system to identify and neutralize foreign objects such as bacteria and viruses.

Answer 249

A

Immunoglobulins are globular.

Answer 250

A

Collagen is composed of three interwoven polypeptide chains, and is found in fibrous tissues such as tendons, ligaments, skin, bones and blood vessels. It serves to help our structure and support body tissues.

Answer 251

A

Collagen is fibrous.

Answer 252

A

An enzyme is a biological catalyst which speeds up te rate of reactions.

Answer 253

A

All enzymes have an active side whose shape is complementary to the substrate molecule(s).Enzymes are specific meaning that they can only speed the reaction of a specific substrate.

Answer 254

A

Enzymes are shaped complementary to a substrate.2.Substrate moves into the enzyme and locks in. 3.An enzyme substrate complex is formed.4.A chemical reaction happens. The substrate is turned into products. Enzyme may act as catabolic or anabolic. 5. Products move out of enzyme 6. Enzyme is ready to accept another substrate molecule

Answer 255

A

Enzymes’ active side and substrates have complementary shapes, so that the substrate fits into the enzyme like a key. This is called a lock and key model of enzyme action.A different kind of substrate cannot fit as the shape needs to fit perfectly. This makes enzymes specific. They are specific in order to make different products that the protein is assigned to.

Answer 256

A

Enzymes are globular proteins.

Answer 257

A

The enzyme will be denatured. Denaturing refers to a permanent structural change in a protein that results in a loss of its properties Denaturing causes a change of shape of the active side of the enzyme which means it will not function anymore.

Answer 258

A

As temperature increases, relative activity increases until the enzymes is denatured where it will rapidly fall.

Answer 259

A

As pH increases towards its optimum pH, relative activity increases. As pH increases away from its optimum pH, activity decreases.

Answer 260

A

As concentration increases, activity increases to its point of saturation. Beyond the point of saturation, the increase in concentration remains constant.

Answer 261

A

As temperature increases, increases due to collision theory. As higher temperatures cause more movement, collisions occur more frequently. As temperature increases beyond the optimum temperature, the enzyme will denature causing activity to slow down rapidly.

Answer 262

A

As the pH increases, enzymes are closer to their optimum pH where they work most efficiently. As pH increases beyond the optimum pH, the enzyme slowly starts to denature, slowing the activity.

Answer 263

A

When substrate concentration increases, collision frequency increases as there are more substrates enzymes can react with. After reaching point of saturation, activity can no longer be increase regardless of increase in substrates, as all enzymes are bound and reacting at maximum rate

Answer 264

A

Immobilized enzymes are enzymes which are restricted from movement and are in a fixed space.

Answer 265

A

Immobilized enzymes are used in many industries. 1. Production of lactose free milk by having the enzyme lactase.2. Production of sodas where glucose isomerase is used to break glucose to fructose to make the drinks sweeter3. Production of fruit juice to break down pectin which makes it cloudy with the enzyme pectinase. 4. Biological washing powder contains protease, amylases and lipases. This makes it effective at breaking down food stains in low temperature that saves household costs.

Answer 266

A

Lactase breaks down lactose into glucose and galactose This creates lactose free milk which can be enjoyed by consumers around the world, regardless of whether they are lactose intolerant or not.

Answer 267

A

Allows people who are lactose intolerant to consume milk products. 2. It makes the milk taste sweeter, because glucose and galactose taster sweeter than lactose. This is good for smoothies and milk shakes. 3. Glucose and galactose are more soluble, making milk smoother and ice cream less crystallized. 4. It reduces production time for yogurt and cheese, as glucose and galactose are quicker to ferment than lactose.

Answer 268

A

DNA consists of many nucleotides. This is called a polynucleotide.

Answer 269

A

DNA polynucleotide monomers are linked together by covalent bonds into single strand DNA polymers.

Answer 270

A

Composed of deoxyribose sugar, nitrogenous bases and phosphorus group.

Answer 271

A

A - Adenine G - GuanineT - Thymine C - Cytosine (Always go to chemistry)

Answer 272

A

Adenine is complementary to Thymine. Double Hydrogen Bond.

Answer 273

A

Cytosine is complementary to Guanine. Triple Hydrogen Bond.

Answer 274

A

Adenine double bond ThymineCytosine triple bond Guanine

Answer 275

A

Adenine and Guanine are purines.

Answer 276

A

Thymine and Cytosine are pyrimidine.

Answer 277

A

DNA strands are antiparallel to form a double helix. Include: - Sugar phosphate backbone - complementary base pairs - Hydrogen bases between bases of two strands (dotted line)

Answer 278

A

a DNA polynucleotide is a double stranded helix. The DNA strands are antiparallel linked by hydrogen bonds between the complementary nitrogenous base pairs.

Answer 279

A

RNA is a polynucleotide. RNA nucleotide monomers are linked together by covalent bonds into single stranded DNA polymers.

Answer 280

A

RNA nucleotides are composed of ribose, one sugar phosphate group and a nitrogenous base.

Answer 281

A

Adenine and Uracil Cytosine and Guanine

Answer 282

A

Include sugar phosphate backbone.

Answer 283

A

Similarities:
* Both have sugar phosphate groups
* Both have nitrogenous bases
* Both have pentose sugars
* Both are poly nucleotides
* Both have covalent bonds
* Both have sugar phosphate backbones
* Both have Adenine and Guanine as purines
* Both store genetic information
Differences:
* DNA has deoxyribose. RNA has ribose
* DNA is a double helix and is therfore double stranded. RNA is single stranded DNA must have hydrogen bonds between the nitrogen bases. RNA is mainly covalently bonded and onlyoccasionallyhas hydrogen bonds.
* DNA has Thymine and Cytosine as pyrimidines. RNA has Uracil and Cytosine as pyrimidines.
* DNA has an anti-parallel structure. RNA with only one strand has only one direction. 5’ to 3’

Answer 284

A

As we know that DNA has a double stranded structure, and is defined by their sequence in order to store genetic information, we can deduct that a replication of a strand can be created through the information of the complementary strand.

Answer 285

A

Phages were attached to a bacterial cell. 2. The DNA is transferred through injection into the bacterial cell.3. Phage had normal DNA but was covered in radioactive protein coat4. Phages were attached to bacterial cell, and DNA was transferred and reproduced. Next generation was not radioactive. 5. Phage had radioactive DNA covered in normal protein coat.6. Next generation was radioactive.

Answer 286

A

A phage is a type of virus that infects bacteria. Phages are made from DNA covered with a coat of protein.

Answer 287

A

From the experiment we can deduce that protein does not pass on genetic information or even contain such.From the experiment we can also deduce that DNA is inherited by the next generation. Therefore, DNA stores genetic material that is information needed for the next generation

Answer 288

A

From the crystallography we can find that strands over lap like intersections and therefore DNA should be a double stranded helix.

Answer 289

A

In DNA replication, DNA Helicase unzips the double stranded DNA helix by breaking apart the hydrogen bonds.

Answer 290

A

DNA gyrase releases tension from the DNA double helix. It does this by breaking both strands and unwinding the strand by 2 coils and then fusing the DNA strands back together.

Answer 291

A

DNA polymerase I replaces the RNA strand with a DNA strand.

Answer 292

A

DNA polymerase builds complementary DNA strands (sugar phosphate backbone)

Answer 293

A

Single stranded binding proteins prevent the single DNA strands from sticking back together.

Answer 294

A

DNA primase inserts a piece of RNA to the single strand

Answer 295

A

Are the sections of DNA on the lagging strand that need to be connected

Answer 296

A

DNA polymerase II uses dNTP (Deoxynucleotide triphosphate) to build a new complementary strand of DNA (connecting the Okazaki fragments). Two phosphate groups are removed

Answer 297

A

DNA ligase is responsible for joining the Okazaki fragments to create a continuous strand.

Answer 298

A

○ Helicase ○ DNA gyrase ○ single strand binding proteins ○ DNA primase ○ DNA polymerases I ○ DNA polymerases III ○ Okazaki fragments ○ deoxynucleoside triphosphates (dNTPs) - also known as ‘free nucleotides’

Answer 299

A

DNA replication occurs in a 5’ to 3’ direction because DNA polymerase 3 only adds nucleotides to the 3’ end of the primer.

Answer 300

A

DNA helicase unzips the double stranded DNA helix by breaking the hydrogen bonds 2. The single stranded binding proteins attach themselves to each strand to prevent them from sticking back together. 3. DNA Primase adds a new RNA strand to the single strand.4. DNA polymerase III builds a new complementary DNA strand. The existing strand is used as a template using the complementary base pairing rules5. DNA polymerase I replaces the RNA primer with a short DNA strand. On the leading strand DNA polymerase III can build a complementary DNA strand continuously.

Answer 301

A

On lagging strand the new complementary DNA strand must be built in sections called Okazaki fragments due to the fact that the DNA polymerase III only goes in one direction, 5’ to 3’2. DNA ligase is required to join together the Okazaki fragments. On the lagging strand DNA polymerase III has to work discontinuously because it only works in one direction from 5’ to 3’

Answer 302

A

DNA replication initiates at many points in eukaryotic chromosomes. This is because eukaryotic genomes are usually larger than prokaryotic genomes. So DNA is replicated at many points simultaneously in order to limit the time required for DNA replication to occur.

Answer 303

A

These sites are called origins of replication and form replication bubbles.As replication bubbles expand they eventually fuse together. Two generate two separate semi conservative double strands of DNA

Answer 304

A

DNA replication is semiconservative. One strand will form from the original DNA strands. One strand will be newly synthesized.

Answer 305

A

Meselson and Stahl grew an E.Coli bacteria in a medium containing N15 Nitrogen atoms. After several generations all of the bacteria contained heavy DNA with two strands made from N15.Then the E.Coli bacteria was transferred into a medium containing N14 nitrogen Scientists allowed bacteria to complete 1 cell division by binary fission. They then took samples of the cells and tested the DNA in a centrifuge to measure its weight. The bacteria then was allowed to complete several more replications by binary fission. Each time DNA was taken and measured in a centrifuge.

Answer 306

A

From Melson and Stahl’s we can deduct that DNA replication is semi conservative as there is as DNA is always semi-transferred and semi conserved into the new generation.

Answer 307

A

DNA polymerase uses the complementary base pairing rules to determine the sequence of nucleotides as it builds a new strand of DNA. This ensures that the two daughter cells produced by mitosis are genetically identical

Answer 308

A

Taq polymerase is a thermo-stable DNA polymerase enzyme. This is enzyme is found from the heat loving bacteria, thus does not denature at extreme temperatures.

Answer 309

A

Taq polymerase performs the same role as DNA polymerase by producing several copies of of DNA during polymerase chain reaction. In order to artificially replicate human DNA.

Answer 310

A

One gene holds information to make one polypeptide. (A gene is a section of the DNA)

Answer 311

A

Process takes place inside the nucleus1. RNA polymerase will attach it self to the promoter site of the DNA.2. RNA polymerase unwinds the DNA by breaking hydrogen bonds. This creates a transcription bubble.3. RNA polymerase will build a new strand using complementary base pairing rules to pair RNA nucleotides along the anti sense strand. 4. RNA polymerase reaches terminator where transcription is completed. 5. RNA polymerase breaks away from DNA6. DNA double helix rewinds and mRNA is released

Answer 312

A

mRNA (messenger = transcription)tRNA (transfer = translation)rRNA (ribosome = translation)

Answer 313

A

Small ribosome sub-unit attaches itself to mRNA strand. 2. mRNA is made of codons which is a sequence of 3 consecutive RNA bases. tRNA has anti codons which is also made of 3 consecutive RNA bases. A tRNA molecule always corresponds to a specific amino acid. 3. Ribosomes will read the codons on the mRNA and using complementary base pairing rules, pair appropriate tRNA molecules. 4. The ribosome works its way along the mRNA in direction of 5’ to 3’. Until it finished building the polypeptide chain.

Answer 314

A

In a cell’s cytoplasm

Answer 315

A

G1 and G2 Phase

Answer 316

A

Translation happens in order to make polypeptides for protein synthesis.

Answer 317

A

The role of a ribosome is to read the base sequence of the mRNA and use this information to build a polypeptide.

Answer 318

A

The role of mRNA is to hold genetic information from the nucleus to the ribosome.

Answer 319

A

The role of tRNA is to bring specific amino acids to the ribosomes for protein synthesis.

Answer 320

A

As the sequence of mRNA is composed of codons it directly corresponds to an anti codon with its specific amino acid that is always the same for the specific code. Thus, the amino acid sequence is determined by the genetic code.

Answer 321

A

Amino acids are determined by the mRNA and not the tRNA.

Answer 322

A

GMO means genetically modified organisms.

Answer 323

A

The production of human insulin in bacteria is a demonstration as to how bacteria can be genetically modified through transfer of gene. This is done by replacing a gene for human insulin into a bacterial plasmid, which in the bacterial organism will produce human insulin to treat diabetics.

Answer 324

A

In eukaryotic cells, the mRNA has to be modified after transcription.

Answer 325

A

Eukarytoic RNA has to remove introns.

Answer 326

A

mRNA splicing has to function to remove unnecessary non-coding regions before translation. Introns allow cells to make a variety of slightly different polypeptides from the same gene. Sometimes an intron can be included in the mRNA. This will produce a slightly different polypeptide. Thus a slightly modified protein.

Answer 327

A

A promoter site is an example of a non-coding DNA with a function.

Answer 328

A

Cell specialization occurs through a process of differentiation where genes are swicthed off.

Answer 329

A

The environment plays a major role in affecting whether genes are switched off or on. It has an effect of the gene expression.

Answer 330

A

It is the ability of an organism to develop in different ways according to its environment.

Answer 331

A

One nucleosome is made of 8 histone proteins, with DNA wrapped around the outside. Only eukaryotic cells have nucleosomes.

Answer 332

A

Nucleosomes protect DNA from damageThey allow long lengths of DNA to be supercoiled for mobility of mitosis.Nucleosomes help to regulate DNA transcription.

Answer 333

A

While a DNA strand is wrapped around a histone protein, in a nucleosome, the enzyme RNA polymerase cannot unwrap the DNA double helix for transcription to occur. Some parts of a cell’s DNA is permanently wrapped into nucleosomes that permanently switch off the gene.

Answer 334

A

No. Prokaryotic cells have naked DNA meaning that they do not have histone proteins to form nucleosomes.

Answer 335

A

Through proteins, gene expression can be regulated and therefore temporarily regulated. This happens when proteins bind to specific base sequences in the DNA, such a promoting protein or a blocking protein on the operator site.

Answer 336

A

Ribosomes are made of rRNA and proteins.It is composed of 2 sub-units: a large sub-unit and a small sub-unit. It consists of 3 binding sites for tRNA.It has one binding site for mRNA.

Answer 337

A

A tRNA molecule is a polynucleotide chain. It is folded back to form a region of double helix, according to RNA complementary base pairing rule.It contains 3 loops.It contains an anti-codon with 3 RNA bases.It has a binding site for an amino acid.

Answer 338

A

tRNA molecule has to be linked to a specific amino acid through a tRNA - activating enzyme. 1. Specific amino acid binds to active side of a tRNA-activating enzyme.2. ATP binds to active site of the enzyme to provide energy stored in the 3 phosphate groups.3. 2 of the phosphate groups break away which releases energy captured by the amino acid.4. A specific tRNA molecule binds to the active site of tRNA activating enzyme which active site has to be complementary to the anti codon of tRNA. 5. High energy bond between the amino acid and tRNA molecule is formed which activates the tRNA molecule. The energy carried by the tRNA molecule will be used for to form a peptide bond. 6. The tRNA molecules leaves the enzyme to find a ribosome

Answer 339

A

tRNA activating enzyme is an example of enzyme-substrate specificity

Answer 340

A

Initiation 1. The small ribosome sub-unit binds to the mRNA 2. The complementary anti-codon of the tRNA molecule binds to with the start codon at the P-Site3. The large sub-unit of the ribosome binds to the mRNA.

Answer 341

A

Elongation 1. A second tRNA molecule moves into the A-site2. A peptide bond forms between the two amino acids held in A Site and P site.

Answer 342

A

Translocation1. The ribosome moves 3 nucleotides along the mRNA strand.2. the first tRNA molecule moves into E-site and exits the ribosome 3. A-Site is available for a new tRNA molecule.

Answer 343

A

Termination1. Eventually the ribosome will reach the stop codon 2. The ribosome breaks apart into two sub-units Polypeptide is complete.

Answer 344

A

5’ to 3’ direction

Answer 345

A

Free ribosome: make protein primarily for inside the cell.Ribosome on RER: make protein for export out of the cell or for lysosome (i.e. hormones such as insulin)

Answer 346

A

No. Translation in prokaryotes can occur immediately after transcription due to the absence of the nuclear membrane.

Answer 347

A

A polysome is formed when several free ribosome attach themselves to the same strand of mRNA. The advantage of this is that it produces the same amount of polypeptides in a shorter amount of time.

Answer 348

A

Hydrogen BondsDisulfide bridgesIonic BondsHydrophobic Interactions (Inter molecular Forces)

Answer 349

A

Genome is the whole of the genetic information of an organism.

Answer 350

A

Gene is a heritable factor that controls a specific characteristic.

Answer 351

A

An allele is one of a number of different version of a gene

Answer 352

A

The HGP is an international research effort to sequence , map and understand all the genes of members of species, homeosapiens. 18 different countries were involved. It began in 1990 and finished in 2003

Answer 353

A

By being able to read nature’s complete genetic blueprint of a human being:- to learn about the causes of genetic diseases and thus find cures and treatments.- to discover more about how different people are related to each other and to other species /evolutionary relationships - to understand more about the aging process

Answer 354

A

Gene mutation is natural process that causes changes in the DNA sequence caused by a mutagen. The change in DNA sequence causes a change in mRNA, and amino acid sequence and thus produce new alleles.

Answer 355

A

Mutagen is a physical or chemical factor that causes a change in DNA base sequence.

Answer 356

A

There negative effects of mutations such as cancer. Positive effects of mutation are the creation of new alleles for adaption. Sometimes there are no consequences at all as the it codes for the same amino acid.

Answer 357

A

Base substitution mutation is a change of a single base in a sequence of DNA. Example: Sickle Cell Anemia Base substitution mutation: - the sequence of nucleotide bases in DNA codes for the sequence of amino acids in proteins- DNA is transcribed into mRNA, which is translated into amino acids of protein- normal (ß chain) hemoglobin gene / DNA produces - normal (ß chain) hemoglobin protein / amino acidssubstitution= the replacement of one (or more) nucleotide base with another- caused by a copying mistake during DNA replicationas a result of a mutagen / X-rays / chemical / UV radiation / other mutagen- mutation in normal (ß chain) hemoglobin gene alters the sequence of nucleotide bases- normal nucleotide sequence = CTC altered to CACresulting in altered mRNA (GAG to GUG) during transcription- resulting in altered sequence of amino acids in (ß chain) hemoglobin protein (glutamic acid to valine) during translation- causing red blood cells to change shape / sickle under low oxygen conditions- causing sickle cells anemia when two copies of the mutated gene are inherited- producing a sickle cell carrier when one copy of the mutated gene is inherited- sickle cells anemia reduces oxygen flow to organs, leading to their deterioration

Answer 358

A

Prokaryotes have one chromosome consisting of a circular DNA molecule. Eukaryotes have chromosomes that have linear DNA molecules.Prokaryotic DNA is naked. Eukaryotic DNA molecules are wrapped around histone proteins. The circular prokaryotic chromosome contains all genes.. Eukaryotes have different chromosomes with different genes.Prokaryotes sometimes have plasmids. Eukaryotes do not.

Answer 359

A

Homologous chromosomes carry the same sequence of genes but not necessarily the same alleles.

Answer 360

A

A diploid nucleus contain two copies of each homologous chromosome/ have pairs of homologous chromosome/ two chromosomes of each type. number of chromosomes = 2N

Answer 361

A

A haploid nuclei has one chromosome of each homologous chromosome. number of chromosomes = N

Answer 362

A

Due to developments in scientific research, improvements were made in their techniques that included using autoradiography to establish the length of DNA molecules in chromosomes as they discovered specific substances located in cells/tissues.

Answer 363

A

Number of chromosomes is a characteristic feature of members of a species.

Answer 364

A

Gender is determined by sex chromosomes.

Answer 365

A

Autosomal chromosomes are chromosomes that determine the sex. (1st to 22nd Pair)

Answer 366

A

We can identify the gender.We can identify chromosomal abnormalities in health.

Answer 367

A

Karyograms show the chromosomes of an organism in homologous pairs of decreasing length

Answer 368

A

If there are three copies of chromosome 21 instead of two, the individual as down syndrome. Some of the component features of the syndrome are hearing loss, heart and vision disorder. Mental and growth retardation are also very common.

Answer 369

A

radioactively labelled chromosomes of the DNA by growing them in a medium containing thymidine- Using an enzyme cell walls were digested so that cells could release their DNA- a thin film of photographic emulsion was applied to the membrane so that when DNA decayed, it reacted with the film - Dark grains are seen where DNA decayed which indicates the position.

Answer 370

A

Chimpanzees

Answer 371

A

Amniocentesis and chorionic villus sampling are two methods to collect the amniotic fluid.

Answer 372

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Meiosis is one of the two ways in which the nucleus of a eukaryotic cell can divide. (The other is Mitosis)

Answer 373

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Meiosis allows the halving of chromosome numbers that allow sexual life cycle with fusion of gametes. This allows genetic variation.

Answer 374

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Meiosis can happen at any stage during sexual life cycle, but in animals it happens during the process of creating the gametes. Body cells are diploid.

Answer 375

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Interphase2. Prophase I3. Metaphase I4. Anaphase I5. Telophase I/Cytokinesis6. Prophase II7. Metaphase II8. Anaphase II9. Telophase II

Answer 376

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During the last stage of interface, DNA is replicated.

Answer 377

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Nuclear membrane breaks down2. Homologous chromosomes pair up to form bivalents/tetrads.3. Homologous chromosomes are held together by points called chiasma4. Homologous chromosomes undergo a process called synapsis whereby sections of DNA are exchanged between homologous chromosomes.5. Crossing over of genetic material between non-sister chromatids can occur at these points, resulting in new gene combinations (recombination)

Answer 378

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Centrioles form on either side of the cell2. Microtubulos grow and attach themselves to the centromeres of homologous tetrads3. Homologous tetrads line up along the equator

Answer 379

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Homologous chromosomes split apart and move to opposite poles

Answer 380

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Nuclear membrane reforms 2. Centrioles and microtubules break down 3. Cell splits into two haploid daughter cells as cytokinesis occurs.

Answer 381

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Nuclear membrane breaks down

Answer 382

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Chromosomes line up along the equator of the cell 2. Spindle fibres reform and reconnect to the chromosomes

Answer 383

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Spindle fibers shorten and pull sister chromatids apart as they move to opposite poles.

Answer 384

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The cell splits in two as cytokinesis happens concurrently.

Answer 385

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Because sister chromatids may no longer be genetically identical as a result of potential recombination, the process of meiosis results in the formation of four genetically distinct haploid daughter cells.

Answer 386

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Crossing over involves the exchange of segments of DNA between homologous chromosomes.During synapsis in prophase I, homologous chromosomes pair up to form bivalents/tetrads. Portions of non-sister chromatids overlap. The positions in which they are attached are called chiasma.The chromatids break at chiasmata, reattach to new sister chromatids in a system of reciprocal exchange. The new combinations are known as recombinants.

Answer 387

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Random orientation of bivalents/Independent Assortment: Bivalents line up along the equator in metaphase I. This means that chromosomes assort independently into two daughter cells during anaphase I. Chromosomes align along the equator independently during metaphase II. This means that chromatids assort independently into daughter cells during anaphase II2. Chiasma formation:During Prophase I, genetic exchange occurs between homologous chromosome during synapsis. This creates chromosomes with new combinations of alleles. 3. Offspring of sexual reproduction have two parents (Fusion of gametes)

Answer 388

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Non-disjunction can cause Down syndrome.The failure of the chromosomes to separate may either occur via:
* Failure of homologues to separate during Anaphase I (resulting in four affected daughter cells)
* Failure of sister chromatids to separate during Anaphase II (resulting in two affected daughter cells)
Thus, both of the chromosomes move to one pole while none to the other.This results the gametes, sperms or eggs, to have incorrect number of chromosomes.Down syndrome (trisomy 21) is an example. The person would have three homologous chromosomes #21.

Answer 389

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independent assortment: - variety produced by recombination of maternal and paternal chromosomes- for each pair of homologous chromosomes, maternal and paternal chromosomes assort to daughter cells randomly- possible arrangements of chromosomes in haploid daughter cells = (2)nth, where n = number of homologous pairscrossing over: - variety produced by recombination within individual chromosomes- during synapsis, prophase I, homologous chromosomes pair forming bivalents- portions of non-sister chromatids overlap, break at chiasmata, reattach to new chromatid in a system of reciprocal exchange- new combinations known as recombinants

Answer 390

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Phenotype is an observable trait or characteristic.

Answer 391

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Genotype is an organism’s genetic make up

Answer 392

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An allele is a version of a gene.

Answer 393

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An allele which determines the phenotype of a heterozygote.

Answer 394

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An allele which can only influence the phenotype of a homozygote.

Answer 395

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A position in a chromosome.

Answer 396

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An organism is homozygous when it has two identical alleles of the same gene.

Answer 397

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An organism is heterozygous when it has two different alleles of the same gene.

Answer 398

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Testing a suspected heterozygote by crossing it with a known homozygous recessive.

Answer 399

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A monohybrid cross determines the allele combinations of offspring for one particular gene only (HL students may refer to topic 10.2 for dihybrid crosses)

Answer 400

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The parent of unknown genotype is heterozygous.

Answer 401

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a) Bbb) bbc) 50% Brown hair & 50% blond hair

Answer 402

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A genetic cross is a means of determining the genetic characteristics of potential offspring based on the genetic characteristics of the prospective parents.By test crossing we can determine the parent’s unknown genotype.

Answer 403

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Codominance means that two different alleles both affect the phenotype of a heterozygote.

Answer 404

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A gene can have multiple alleles that means more than 2 versions of the same gene.

Answer 405

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ABO blood groups have codominant alleles as well as more than 2 alleles for the same gene. (Recessive allele is i which does not produce glycoprotein. Phenotype = Blood group O)

Answer 406

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Sex linkage occurs when a gene is located on one the sex chromosomes (chromosome #23)

Answer 407

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Red Green Color Blindness & Hemophilia are both examples of X-linked recessive conditionsThe gene loci for these conditions are found on the non-homologous region of the X chromosome (they are not present of the Y chromosome)As males only have one allele for this gene they cannot be a carrier for the condition This means they have a higher frequency of being recessive and expressing the traitMales will always inherit an X-linked recessive condition from their motherFemales will only inherit an X-linked recessive condition if they receive a recessive allele from both parents

Answer 408

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No. As human females have two X chromosomes (and therefore two alleles for any given X-linked gene), they can be either homozygous or heterozygousMales only have one X chromosome (and therefore only one allele) and are hemizygous

Answer 409

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An individual with a recessive allele for a disease condition that is masked by a normal dominant allele is said to be a carrierCarriers are heterozygous and can potentially pass the trait on to the next generation, but do not suffer from the defective condition themselvesFemales can be carriers for X-linked recessive conditions because they have two X chromosomes - males (XY) cannot be carriersBecause a male only inherits an X chromosome from his mother, his chances of inheriting the disease condition from a carrier mother is greater

Answer 410

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Many genetic diseases in humans are caused due the recessive allele of autosomal genes, although some genetic diseases are due to dominant or codominant alleles.

Answer 411

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• Autosomal disease • Recessive• C = healthy/ c = cystic fibrosis• Suffers produce a thick mucus in their lungs which gives them trouble breathing• No cure, no effective treatment.

Answer 412

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Autosomal Dominant
H = Huntington’s disease h = healthy
patients incur damage to nerve tissues, mental decline aged 30+

Answer 413

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• Large sample sizes increases reliability of the data• Large sample sizes reduce the impact of random effects/ small sample sizes increases the impact of random effects

Answer 414

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Mutagens a physical or chemical factor that causes DNA mutations • Physical (UV rays, gamma radiation, X-rays) • Chemical (polonium, radium, dioxins, carbon monoxide, uranium)

Answer 415

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• Higher rate of cancer among survivors • Blood disorders (e.g. Leukemia)• Down syndrome • Soil contamination

Answer 416

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A dihybrid cross determines the allele combinations of offspring for two particular genes that are unlinked (not on the same chromosome)To work out gamete combinations remember FOIL:• First (AaBb = AB)• Outside (AaBb = Ab)• Inside (AaBb = aB)• Last (AaBb = ab)

Answer 417

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Chi squared/ X2Degrees of freedom are determined by the number of types of offsprings, minus one.

Answer 418

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crossing over/chiasmata formed during prophase I of meiosis;
pairing of homologous chromosomes/synapsis; chromatids break (at same point); (do not accept chromatids overlap)
non-sister chromatids join up/swap/exchange alleles/parts;
X-shaped structure formed / chiasmata are X-shaped structures;
chiasma formed at position where crossing over occurred;
chiasmata become visible when homologous chromosomes unpair;
chiasma holds homologous chromosomes together (until anaphase

Answer 419

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Recombinants formed by crossing over

Answer 420

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Meiosis divides the chromosomes into groups of four. Each allele for one trait has a 50% chance of being passed on. But the two alleles combined make four different options, which makes the chances for these being passed on 25%.

Answer 421

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The alleles of two genes pass into gametes without influencing each other.

Answer 422

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When two genes are located on the same autosomal chromosome

Answer 423

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When many genes control the same phenotype (or characteristics). A good example is skin colour.

Answer 424

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The phenotypes of polygenic characteristics tend to show continuous variation

Answer 425

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Unlinked genes assort independently in a dihybrid cross between heterozygotes, producing a 9:3:3:1 phenotypic ratio Linked genes, without crossing over, do not follow the expected 9:3:3:1 phenotypic ratio for a dihybrid cross between heterozygotes
* Instead the result will follow the 3:1 phenotypic ratio of a monohybrid cross, as the two linked genes are inherited together
* This means that all the offspring will produce parental phenotypes
Linked genes with crossing over produce recombinant phenotypes in numbers that reflect the distance between the linked genes
* distant genes will cross over more frequently, producing a higher percentage of recombinants
* genes that are close together will cross over less frequently, producing a lower percentage of recombinants
A test cross involving two linked genes, A and C: AaCc x aacc
* 80% of offspring are parental, either AaCc or aacc
* 20% of offspring are recombinant, Aacc or aaCc
* thus, the two genes are linked and are 20 cM apart on the same chromosome

Answer 426

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DNA is collected and heated to a very high temperature to break the hydrogen bonds between the double stranded DNA. 2. When the mixture is then slightly cooled, DNA primers are inserted using DNA complementary base pairing rules that form hydrogen bonds.3. When the mixture heats up again, Taq polymerase i added to create a new complementary strand of DNA using free DNA nucleotides and the base pairing rules4. This process repeats several dozen times so that millions of copies are produced

Answer 427

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Amplification

Answer 428

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Only minute/very small amount of DNA is needed to amplify.

Answer 429

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Gel electrophoresis is used to separate proteins or fragments of DNA according to size.

Answer 430

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Amplification/PCR, restriction enzymes to cut the DNA, gel electrophoresis to separate the DNA fragments.

Answer 431

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When DNA is in fragments, they can be placed into the gel.An electric field is applied which makes the molecules move to their opposite charge. The smallest fragments travel furthest towards positive charge. UV probe is used to make them visible.

Answer 432

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Solving crimes, Identifying paternity & analyzing evolutionary relationships.

Answer 433

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Genetically modified organisms where gene transfer between specifies has been carried out.

Answer 434

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Production of Human InsulinStep 1: Bacteria has plasmids that contain a small ring of naked DNA that can be copied and shared with other bacteria in order to share useful genesStep 2: Restriction enzymes are used to cut the plasmid DNA. Step 3: The gene for human insulin is inserted into the Plasmid. The sticky ends of the gene and the plasmid have to be complementary. DNA ligase sticks them together. The plasmid has now a recombinant DNA.Step 4: The plasmid is inserted back into the bacteria where it acts as a vector. Step 5: Under a suitable environment, the bacteria will quickly reproduce and be able to synthesize protein for human insulin due to the recombinant DNA.

Answer 435

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Golden Rice: Was enriched with Vitamin A which helps improve the health of poor rural communities whose diet is dependent on rice but lack Vitamin A levels. However, may go against religious, cultural heritage and beliefs because the food is no longer pure. Poor communities may become dependent on the golden rice and not focus on a general improvement in their diet. Bt corn: Bt corn has increased resistance to attack from insects, farmers need to use less insecticide. This reduces the cost of farming as well as environmental contaminationBt corn plants have been genetically engineered to produce a toxic chemical that kills insects. This chemical is also present in the harvested crop. This may pose a threat to human health

Answer 436

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MUST have examples:Benefits:• benefits include more specific (less random) breeding than with traditional methods• faster than traditional methods•some characteristics from other species are unlikely in the gene pool / selective breeding cannot produce desired phenotype•increased productivity of food production / less land required for production• less use of chemical (e.g. pesticides in Bt Corn)• food production possible in extreme conditions (Amflora - GM potatoes are cold/drought resistant)• less expensive drug preparation e.g. pharmaceuticals in milk• human insulin engineered so no allergic reactions• may cure genetic diseasesRisks:• Could have currently unknown harmful effects (e.g. toxin may cause allergic reactions in a percentage of the population)• Accidental release of transgenic organism into the environment may result in competition with native plant species• Possibility of cross pollination (if gene crosses the species barrier and is introduced to weeds, may have a hard time controlling weed growth)• Reduces genetic variation / biodiversity (corn borer may play a crucial role in local ecosystem)

Answer 437

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Clones are a group of genetically identical organisms or a group of cells derived from a single parent cell

Answer 438

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No. Cloning can occur naturally for some animal species and many plants such as potatoes, garlic, onions and wild strawberries.

Answer 439

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Cloning at embryo stage:Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cellsCloning at adult stage:using somatic-cell which are differentiated cell transfer

Answer 440

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Remove a somatic cell (usually a skin cell) from the mouse that you want to clone.Obtain an egg cell from another organism2. Remove the nucleus from the egg cell using a harp pipette. The egg now contains no DNA which makes it enucleated 3. Remove the nucleus from the somatic cell using a sharp pipette4. The nucleus from the somatic cell is injected into the enucleated egg cell5. The cloned cell is treated with chemicals in order to stimulate it to begin cell division which makes a cloned embryo6. Implant the cloned embryo into the uterus of a surrogate organism. Once pregnancy is completed, the surrogate will give birth to the cloned organism

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Biology Unit 1-5 (no 4) Flashcards

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