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Biology > Variation And Inheritance > Flashcards

Variation And Inheritance Flashcards

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AP® Biology flashcards Biology 101 flashcards
0
Q

What do chromosome threads carry

A

Genes

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1
Q

Where are chromosomes

A

In the nucleus

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2
Q

How many chromosomes do gametes carry

A

One

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3
Q

The nuclei of male and female sex cells contain

A

One set of genes

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4
Q

Offspring carry how many genes

A

2

One set from each parent

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5
Q

2 main reasons of variation between individuals of the same kind of organism

A

Genes

Environmental

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6
Q

Asexual reproduction. Variation?

A

No.
Does not involve fusion of the gametes
Genetically identical to single parent
Clones

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7
Q

Sexual reproduction. Variation?

A

Yes
Fusion of gametes
Mixing of genetic information

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8
Q

Why is sexual reproduction important

A

Leads to variation

Natural selection can occur so we can evolve

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9
Q

How many pairs of chromosomes do human beings have

A

23 pairs

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10
Q

Sex chromosomes (how many and what does a male and female look like)

A

1 pair of sex chromosomes
XX= female
XY= male

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11
Q

2 types of genes

A

Dominant

Recessive

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12
Q

Phenotype

A

Physical appearance of the genes characteristic

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13
Q

Genotype

A

The genetic makeup

Eg DD or Dd

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14
Q

Homozygous

A

Both alleles the same

Eg DD or dd

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15
Q

Heterozygous

A

The two alleles are different

Eg Dd

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16
Q

Monohybrid inheritance

A

The inheritance of a single characteristic controlled by a pair of alleles

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17
Q

Who observed clear patterns of inheritance on pea plants

A

Gregory Mendel

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18
Q

Chromosomes are made of…

A

DNA (deoxyriboneucleic acid)

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19
Q

What is the structure of DNA

A

Double helix

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20
Q

What are genes

A

Short sections of DNA

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21
Q

How many compounds are in DNA and what are they called

A

4 called bases

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22
Q

What does each gene contain

A

Code to make a specific protein

23
Q

How many bases control the code for an amino acid

A

3

24
Q

Squares of dominant and recessive

A

Punnett squares

25
Q

What is polydactyly

A

A genetic condition where you have extra fingers/toes

26
Q

What allele is polydactyly caused by

A

Dominant allele

27
Q

What is cystic fibrosis

A

An inherited disorder which affects the cell membranes and causes the production of thick sticky mucus.
Affects lungs especially

28
Q

What allele causes cystic fibrosis

A

Recessive

29
Q

Can parents who don’t have cystic fibrosis still have kids with the disease

A

Yes. The parents are called carriers

30
Q

What type of allele causes sickle cell anaemia

A

Recessive

31
Q

What does the recessive gene of sickle cell anaemia do

A

Affects the shape of the red blood cells so they cannot carry oxygen efficiently & they block capillaries causing pain

32
Q

Sickle cell homozygous

A

Don’t usually survive

33
Q

Heterozygous sickle cell

A

Some blood cells affected

But does give them protection from the malaria parasite

34
Q

Homozygous not sickle cell

A

The majority of the population

However they are at risk of malaria

35
Q

Down’s syndrome is caused by

A

A mistake during meiosis when a cell has too many chromosomes
So there is an extra chromosome 21

36
Q

What is a gene probe

A

A probe that will bind to a particular damaged gene or chromosome

37
Q

How does a gene probe work

A

Has a fluorescent chemical on the end
Probe is added to a mixture containing the DNA sample from the embryo
UV light is used to detect the probe
If the probe has attached to the faulty allele it fluoresces

38
Q

Concerns over embryo foetus screening

A

Risk of miscarriage
False positives/negatives (reliable?)
Decisions about terminating pregnancy

39
Q

Positives about embryo screening

A

May give parents more choices / time to prepare for baby with special needs

40
Q

3 ways to take cells from developing foetus’

A

Chorionic villus sampling- transcervical
Chorionic villus sampling- transabdominal
Amniocentesis

41
Q

Clones

A

Offspring produced by asexual reproduction that are genetically identical to its parent organism

42
Q

2 ways of cloning plants

A

Cuttings
Tissue culture
(Take a tissue sample from parent plant. Tissue grown in agar with nutrients and plant hormones. Equals many tiny identical plants. Plant clones planted and grown)

43
Q

Why might you clone an animal or plant

A

High quality

Eg resistance, yield

44
Q

How to clone animals

A

Embryo transplants

45
Q

Embryo transplants explain

A

Embryo with unspecialised cells split into smaller groups of cells
Transplant into host mother
Sometimes genetically modified

46
Q

Adult cell cloning

A

Adult cell of parent animal eg skin cell
Nucleus removed and added into a mature ovum whose nucleus has been removed
Mild electric shock = cells divide forming embryo
Embryo transplanted into womb of host mother
Clone of original born

47
Q

Advantages of adult cell cloning

A

Yield increased. Eg genetically engineered lambs = special protein in milk = uses in medicine
Save from extinction

48
Q

Disadvantages of adult cell cloning

A

Ethics
Limits variation in population so doesn’t help natural selection
Clone humans in future?

49
Q

Genetic engineering

A

A technique for changing the genetic information of a cell

50
Q

Explain how genetic engineering works

A

Gene is cut out of chromosome using an enzyme
Gene is then placed into another chromosome of a different organism A vector (carrier) such as a plasmids or virus may be used to transfer the gene

51
Q

Why do GM crops produce a higher yield

A

Because they often make their own pesticide dorm are herbicide resistant

52
Q

Explain the manufacture of genetically modified insulin

A

Human cell with insulin gene
Insulin gene is cut out of DNA using an enzyme.
Bacteria with a ring of DNA called a plasmid
Plasmid taken out of bacteria and split open using enzyme.
Insulin gene inserted into plasmid using another enzyme.
Plasmid with insulin producing gene is taken up by bacterium
Bacterium multiplies many times, insulin produced and harvested form human injection.

53
Q

Advantages of genetic technology

A

Herds with useful characteristics
Adult cell cloning of copies of the best adapted animals
Faulty gene = genetic disorder. Can be fixed with genetic engineering (in future)
Medical drugs produced
Higher yield of crops = more food per square metre

54
Q

Disadvantages of genetic technology

A

Farmers have to buy GM seeds every year as crops are infertile
Accidentally introducing genes into wild flowers
Insects which aren’t pests?
Eating GM crops? Human health
Ethical
Long term?

Biology (23 decks)

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