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Year 11 Biology > B12-B14 > Flashcards

B12-B14 Flashcards

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1
Q

How many parents are involved in sexual reproduction? How many parents are involved in asexual reproduction

A

There are two parents involved in sexual reproduction

There is only one parent involved in asexual reproduction

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2
Q

What are the gametes(sex cells) involved in sexual reproduction ? What are the gametes involved in asexual reproduction?

A
  • The gametes involved in sexual reproduction for animals are Sperm cells and egg cells
  • The gametes involved in sexual reproduction for plants are egg cells and pollen grains
  • There are no gametes involved in asexual reproduction
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3
Q

Waht do the gametes fuse together to form in asexual and sexual reproduction?

A
  • In sexual reproduction for animals the gametes fuse together to form a zygote
  • In sexual reproduction for plants the gametes fuse together to form a seed
  • There is no fusion of gametes in asexual reproduction
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4
Q

How do cells divide with sexual reproduction ?

A
  • Normal body cells divide by mitosis with sexual reproduction
  • Gametes(sex cells) divide by meiosis with sexual reproduction
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5
Q

How do cells divide with asexual reproduction

A

-cells divide by mitosis with asexual reproduction

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6
Q

Is there variation in the offspring with sexual reproduction?

A

There is variation within the offspring with sexual reproduction as the offspring have DNA from both parents

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7
Q

Is there variation within the offspring with asexual reproduction?

A

There is no variation within the offspring with asexual reproduction ( the offspring are identical to the parents and the other offspring)

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8
Q

What are teh advantages of sexual reproduction

A
  • sexual reproduction creates variation within the offspring
  • If the environment changes variation gives a survival advantage
  • humans can selectivly breed organsims that sexually reproduce to increase food productiom
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9
Q

What are the advantages of asexual repeoduction

A
  • only one parent is needed for asexual reproduction
  • Asexual reproduction is more time efficient as there is no need to find a mate
  • Asexual reproduction is faster than sexual reproduction
  • Many identical offspring can be produced during asexual reproduction in favouable conditions
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10
Q

What are some examples of organisms that reproduce asexually ?

A
  • Bacteria reproduce asexually
  • Strawberry plants reproduce asexually
  • Daffodils reproduce asexually
  • The smallest animals repeoduce asexually
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11
Q

What are examples of organisms that reproduce sexually and asexually

A
  • Malarial parasites reproduce asexually in the human host but sexually in a mosquito
  • Many fungi reproduce asexually from spores but also sexually to produce variation
  • Plants reproduce sexually by seeds but also asexually e.g daffodils and strawberry plants
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12
Q

Why is it advantageos for plants to be able to reproduce sexually and asexually

A

It is advantageous for plants to be able to reproduce sexually and asexually as it means they can still reproduce even if their flowers get destroyed

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13
Q

What is meiosis

A

Meiosis is a type of cell division that occurs in the testicles or ovaries to produce non gentically identical gametes/sex cells(sperm and egg cells)

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14
Q

What are the stages in meiosis

A

The stages in meiosis are:

  • the DNA replicates in a cell in a reproductive organso that the cell now has 96 chromosones
  • The cell in the reproductive organ divides to produce two genetically non identical gametes
  • The two genetically non identical gametes split again to produce 4 non identical gametes
  • The gametes each contain a single set of genetically non identical chromosones (23 chromosones in humans)
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15
Q

When does mitosis occur ? When does meiosis occur?

A

Mitosis occurs during the growth and repair of body tissues whereas meiosis occurs during the production of gametes (sex cells)

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16
Q

Where does mitosis happen ? Where does meiosis happen?

A

Mitosis happens in all body cells except for gametes whereas meiosis occurs in cells in the human reproductive organs

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17
Q

What is produced after mitosis ? What is produced after meiosis?

A
  • 2 genetically identical daughter cells are produced after mitosis (each containing 46 chromosones
  • 4 gametes are produced after meiosis(each containing 23 chromosones)
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18
Q

Is there variation in the cells produced after mitosis ? Is there variation in the cells produced after meoisis?

A
  • Two gentically identical daughter cells are formed during mitosis. There is no variation .
  • Four genetically different gametes are formed during meiosis . There is variation as they are different
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19
Q

What is the genome of an organism

A

The genome of an organism is the all of the genetic material for that organism

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20
Q

What is a gene

A

A gene is a small section of a chromosone that codes for a specific sequence of amino acids , to make a particular protien

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21
Q

What is the structure of DNA

A

DNA is a chemical found in the nucleus of cells . It is a polymer made up of two stands joined together. It is as a double stranded ,double-helix molecule

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22
Q

Why do scientists study the genome

A
  • Scientists study the genome to they search for different genes linked to diseases
  • Scientists also study the genome to help them understand and try to treat inherited disorders
  • Scientists also study the genome to help track human migration patterns from the past
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23
Q

What are nucleotides

A

Nucleotides are the building blocks of DNA. They join together to form a double stranded, double-helix molecule

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24
Q

What are nucleotides composed of

A

Nucleotides are composed of a phosphate group, a nitrogenous base and a pentose sugar

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25
Q

Which nucleotide nitogenous bases bond with each other

A

The base ‘A’ only bonds with the base ‘T’

The base ‘C’ only bonds with the base ‘G’

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26
Q

What is a chromosone

A

A chromosone is a long coiled structure composed of DNA and protien

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27
Q

What is an allele

A

An allele is an alternate/different form of a gene e.g if the gene is eye colour the different alleles could be blue eye and brown eye

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28
Q

What is a dominant allele

A

A dominant allele is an allele that is expressed (even if there is only one dominant allele)

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29
Q

What is a recessive allele

A

A recessive allele is an allele that is ‘masked’ by a dominant allele. It is only expressed if both alleles are recessive e.g bb,tt

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30
Q

What is a homozygous genotype

A

A homozygous genotype is where a person has two identical alleles for a specific gene e.g BB ,tt , PP

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31
Q

What is a heterozygous genotype

A

A heterozygous genotype is where a individual has two different alleles for a specific gene

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32
Q

What is a phenotype

A

A phenotype is the phyiscal expression of one’s genotype due to its interaction with the environment e.g tall, small

33
Q

What is the genotype of an organism

A

The genotype of an organism is the genetic constitution of an organism

34
Q

What is a gamete

A

A gamete is a sex cell(sperm cell, egg cell)it has half the number of chromosones of a normal cell

35
Q

What is an example of a dominant disorder

A

An example of a dominant disorder is Polydactyly (having extra figers of toes). It is caused by a dominant allele.

36
Q

Why is an example of a recessive disorder

A

Cycstic fibrosis is an example of a recessive disorder. It is caused by recessive alleles

37
Q

What is a gene mutation

A

A gene mutation is a change to a gene

38
Q

How can gene mutations be caused

A
  • Gene mutations can occur spontaneously(they just happen) r.g during DNA replication
  • Gene mutations can be caused by external factors such as ionsing radiation eg x rays , UV light and chemicals e.g tar in ciggarette smoke
39
Q

When do these mutations occur

A

Gene mutations occur continously but a rarely harmful. They rarely code for a change in protein shape/ faulty protien

40
Q

How does protien synthesis happen ?

A
  1. DNA unzips and uncoils in the nucleus
  2. MRNA molecule takes a complementary copy of the DNA (A-T C-G)
  3. MRNA molecule leaves the nucleus and travels to the ribosomes
  4. The ribosomes read the MRNA molecule in groups of 3 bases
  5. A carrier molecule carries specific a amino acid that is complementary to the codon. Amino acids bond together
  6. Eventually a chain of amino acids called a protein form, this eventually breaks off when a stop codon is reached
41
Q

What does Genetic screening involve

A

Genetic screening involves undergoing tests to see if a person/feotus/ embryo has a genetic disorder or is carrying a faulty allele

42
Q

How can cells be harvested from embryos

A

Cells can be harvested from emebryos by:

  • Amniocentesis
  • Chronic villus sampling
  • analysing feotal cells from the mothers blood
43
Q

What are the advanatages of genetic screening

A
  • The person or family affected can plan ahead and get treatment for the condition
  • The person knows if there is a chance of getting ill in the future
  • Parents can decide wether to have children or not or continue with pregnancy
44
Q

What are the disadvantages of genetic screening

A
  • Screening is expensive
  • There is risk of harm / misscariage for mother and feoutus
  • The tests may not be reliable (false positive / false negative results)
  • Ethically/ morally wrong in some religions
45
Q

Who was Alfred rusell Wallace

A
  • Alfred Russel wallace was a british scientist that developed the theory of speciation
  • On his travels, he came up with the idea that individuals in a species that did not have characteristics to help them survive a change in the environment would die
  • He continued to work across the world to collect evidence to support his theory -One of his most important works was on warning colouration in animals
46
Q

What are the diffeneces between Darwin and Lamarks theory

A
  • Darwin stated that a spcies that had an advantage in its environment would be more likely to survive and reproduce, passing its genes on and therefore the advantage would increase over years and years
  • Lamark stated that changes that occured in an organism during its lifetime e.g aquiring a skill such as playing the piano could then be inherited by the offspring
47
Q

What is a species

A

A species is a group of similar organisms capable of interbreeding to produce fertile offspring

48
Q

What is speciation

A

Speciation is the formation of a new biological species. Speciation is a result of isolation,mutation,selection

49
Q

How does speciation occur

A
  1. A population becomes geographically isolated from an orginal population e.g by continetal drift
  2. There are different environmental conditions for the new population
  3. Mutations may occur,creating variation within the population
  4. A process of natural selection occurs, whereby the individuals best adapted to the environment survive and reproduce
  5. Over time, the new population changes so much it can no longer interbreed to produce fertile offspring with the original population
  6. Speciation has occured
50
Q

How can two populations from the same species form two different new species

A

-If two populations from the same species become so different in phenotype that they can no longer interbreed to produce fertile offspring , two different species have been formed

51
Q

What is the evidence that evolution has/ is occuring

A

The evidence evolution has/is occuring is antiobiotic resistant bacteria and fossils

52
Q

What are fossils

A

Fossils are the remains of organisms from millions of years ago that are found in rocks

53
Q

How do fossils form

A
  • When an organism dies it is covered in sediment/ mud or sinks into mud . The soft parts of the organism decay/are eaten. The bones / harder parts of the organim do not decay so minerals enter the bones and so preserve them
  • Traces of organisms may also become covered by mud and sediment and eventually die
54
Q

We can fossils not be relied upon for evidence of evolution

A
  • Fossils rarely form
  • Fossils can only form under the right conditions
  • Lots of the early organisms were soft bodied so did not produce fossils
  • Some organisms did not form fossils so there are gaps in fossil records
55
Q

How do anitbiotic resistant strain bacteria form

A
  • Bacteria can evolve rapidly as they can reproduce at a fast rate
  • Mutations of bacterial pathogens can produce new strains of bacteria
  • Some straints may be resistant to antibiotics and so are not killed
  • The resistant strain survive and reproduce, so their population increases
  • The resistant strain will then spread as people are not immune to it and tehre is no effective treatment
56
Q

What are some ways to reduce antibiotic resistance

A
  • Always take the full course of antibiotics so all bacteria are killed and none survive and mutate to form resistant strands
  • Doctors should only prescribe antibiotics when needed e.g not for viral infections
  • The agricultural use of antibiotics should be restricted
57
Q

What is extinction

A

Extinction of an organism is when there are no remaining individuals of a species still alive

58
Q

How are humans contributing to species becoming extinct

A

Humans are contributing to species becoming extinct by:

  • habitat destruction
  • Introduced species to an area
  • Over hunting and fishing
  • Climate change/ change to environment
  • Speciation
  • Extinction of a species from the food web
59
Q

What is classification

A

Classification is the way in which living things (organisms) are grouped based on the features( characteristics) that they have in common

More recent classification is based on DNA analysis

60
Q

What did Carl Linneaus do ?

A
  • Carl Linnaeus classified organisms into 5 kingdoms (based om their structure and chracteristics )
  • He classified living things by there kingdom,phylum,class,order,family,genus and spcies
  • He also developed the Binomial naming system
61
Q

What is the binomial naming system

A
  • The binomial naming system was a system developed by Carl Linnaeus that gives a name to each organism
  • The first part if the name is the Genus which the organism belongs to . This is written with a capital letter at the start
  • The second part of the name is the species which the organism belongs to. It is written in lower case letters
62
Q

What did Carl Woese do

A

Carl Woese developed a different classification system using DNA evidence and analysis

-Carl woese divided organisms into three domains in his system

63
Q

What are the three domains of Carl Woese system

A

The three domains of Carl woese system are

  • Archea - Primitive bacteria that usually live in extreme environments
  • Bacteria - true bacteria
  • Eukaryota - Fungi,protists,plants, animals
64
Q

How do you classify an organism (6)

A
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species

Do koalas play clarinet or flute -Great sound

65
Q

What is selective breeding

A

Selective breeding is the process by which humans breed animals and plants for particular genetic characterists

66
Q

What is the process involved in selective breeding

A
  1. Decide on the important characteristic (desirable characteristic) e.eg large muscle mass / blue flower
  2. Choose parents that display this characteristic
  3. Breed the parents together to produce offspring
  4. Select the offspring that have the desired characteristic and breed them together to produce the new generation

5.repeat this process continuosly till all of the organisms have the desired characteristic
5.

67
Q

What are the advantages of selective breeeding

A
  • Selective breeding can produce plants/ animals with desirable characteristics e,g cattle with increase meat and milk yield (which can then increase farmers profits)
  • Selective breeding can produce new varieties of good crops
  • Selective breeding can produce disease resistance in garden plants and crops
  • selective breeding can produce domesticated animals with a gentle nature
68
Q

What are the disadvantages of selective breeding

A
  • Selective breeding often results in a population of plants/ animals with very similar genetics
  • Selective breeding often involves in breeding individuals that are closely related , known as inbreeding
  • Inbred populations are more likely to suffer from genetic confitions caused by recessive alleles as they are more likely to inherit two copies of the recessive variants , one from each parent
  • Inbred populations are more suseptible to disease
69
Q

What does genetic engineering involve

A

Genetic engineering is a process that involves

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

70
Q

What is an organism whos genome has been altered called

A

An organism whose genome has been altered is called a gentically modified organism

71
Q

Describe the process of genetic engineering

A
  • Select the required gene
  • Isolate the gene (using enzymes)
  • Insert the gene into another organism e.g the plasmid of a bacterial cell. This is called the host . Put the vector back into the host(e.g bacterium
  • allow the genetically modified bacterium to reproduce
  • Seperate and purify the product of the gene
72
Q

What are the advantages of genetic engineering

A

1,Organisms with the desired characteristics can be produced rapidly with genetic engineering
2Genetic engineering can improve the quality and yield of crops which then may help to reduce world hunger
3.With genetic enegineering pest and insect resistance can de developed and inserted into plants . This reduces the use of herbicides
4.genetic engineering can improve plants resistance to disease
5.Genetic engineering can be used to introduce herbicide resistance to plants , which results in less herbicides being used as weeds can be selectivley and quickly killed
6.Genetic engineering can improve the shelf life of fruit and veg

73
Q

What are the disadvantages of genetic engineering

A
  • Genetucally engineered plants / animals can damage food chains
  • Genetically engineered food sources could possibly harm humans and animals e.g toxins from genetically engineered crops have been founf in some peoples blood
  • Genetically engineered animals can escape and breed with wild animals
74
Q

What are the four methods of cloning

A
  • Tissue culture of plants
  • Cuttings of plants
  • Embryo transplant cloning
  • Adult cell cloning
75
Q

What is tissue cloning used to di

A

Tissue cloning is used to make new plants using asexul reproduction

76
Q

How do you coduct tissue cloning

A

To conduct tissue cloning
-Small pieces of tissue from a plant are taken and put into a sterile liquid or jelly which contains nutrients and hormones

-Aseptic technique (very sterile ) is used to ensure no bacteria or fungi contaminate the culture

.The plant tissue pieces develop into new plants with roots ,shoots and leaves.They are clones of the
parent plant

77
Q

How can embryo transplant cloning used to create clones of a bull with a high dairy yeild

A

1 . Sperm is taken from a bull with a high dairy yield

  1. This sperm is artifically inseminated into a normal cow
  2. The sperm fetilises the cows egg and zygotes develop . These zygotes develop into embryos in the cow.These embroys are then taken from the uterus of the cow
  3. The embryos taken from the cow are split into several smaller embryos , each of which can grow into a new calf
    - These embryos are placed into the uteruses of foster mothers
  4. New calves are born
78
Q

What does cloning from cuttings involve

A

Cloning from cuttings is where gardeners take cuttings from parent plants and then plant them to produce genetically identical clones of the parent plant

79
Q

Describe the stages in adult cell cloning

A
  1. Take a normal body cell from the organism to be cloned and remove the nucleus(nd keep it)
  2. Take a unfertilised egg cell , remove the nucleus and discard it
  3. Place the normal body cell nucleus into the empty egg cell
  4. Give the egg cell with the human nucleus an electric shock to stimulate cell division into an embryo
  5. Transfer the embryo into the uterus of surrogate organism to develop into a clone

Year 11 Biology (5 decks)

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