B11 - Inheritance Flashcards

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1
Q

Define inheritance.

A

the transmission of genetic information from generation to generation.

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2
Q

Define chromosome.

A

a thread-like structure of DNA, carrying genetic information in the form of genes.

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3
Q

Define gene.

A

a length of DNA that codes for a protein.

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4
Q

Define allele.

A

a version of a gene.

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5
Q

Define haploid nucleus.

A

a nucleus containing a single set of unpaired chromosomes.

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6
Q

Define diploid nucleus.

A

a nucleus containing two sets of chromosomes.

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7
Q

Define mitosis.

A

nuclear division giving rise to genetically identical cells.

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8
Q

Define meiosis.

A

reduction division in which the chromosome number is halved from diploid to haploid resulting in genetically different cells.

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9
Q

Define genotype.

A

the genetic make-up of an organism in terms of the alleles present.

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10
Q

Define phenotype.

A

the observable features of an organism.

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11
Q

Define homozygous.

A

having two identical alleles of a particular gene.

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12
Q

Define heterozygous.

A

having two different alleles of a particular gene.

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13
Q

Define dominant.

A

an allele that is expressed if it is present.

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14
Q

Define recessive.

A

an allele that is only expressed when there is no dominant allele of the gene present.

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15
Q

Define variation.

A

differences between individuals of the same species.

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16
Q

Define mutation.

A

a change in a gene or chromosome.

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17
Q

What are examples of cells with haploid nuclei?

A

gametes / sperm / egg / pollen / ovule

18
Q

What are examples of cells with diploid nuclei?

A

all body cells

19
Q

How many pairs of chromosomes are in human diploid cells?

A

23

20
Q

What is the 23rd pair of chromosomes called?

A

the sex chromosome

21
Q

What is the chromosome pair for males and females?

A

male - XY
female - XX

22
Q

Where is DNA found?

A

the nucleus of cells.

23
Q

What is made of DNA?

A

genes.

24
Q

Why is DNA essential for life?

A

genes determine all our features and cell activity.

25
Q

What four bases make up DNA?

A

adenine, thymine, cytosine, and guanine.

26
Q

Which bases join?

A

adenine and thymine
guanine and cytosine

27
Q

Why is the replication of DNA so important?

A

Enables cell division, mitosis, and produces sex cells.

28
Q

Describe how DNA replicates.

A

A section of DNA ‘unzips’ and separates the bases, spare bases latch on so there are no two identical sections of DNA.

29
Q

What happens to the chromosome number at fertilisation?

A

it is restored/doubled.

30
Q

How many cells does mitosis produce?

A

2

31
Q

What is the role of mitosis?

A

growth, cell replacement during development, in the repair of damaged tissues, and asexual reproduction.

32
Q

What are stem cells?

A

unspecialised cells.

33
Q

What is the role of meiosis?

A

make haploid gametes, to produce genetic variation.

34
Q

What is genetic variation?

A

the differences in genotype.

35
Q

What is phenotypic variation?

A

the differences in phenotype.

36
Q

What is continous variation?

A

when the individuals in a population have a range of phenotypes which vary between two extremes.

37
Q

What is discontinuos variation?

A

when there are two or more disctinct categories. each individual falls into only one of these categories, so there is a limited number of phenotypes.

38
Q

What is natural selection?

A

the increased chance of passing on alleles by the best-adapted organisms.

39
Q

What are the five stages of natural selection?

A

Genetic variation
Overproduction
Struggle for existence
Survival of the fittest
Advantageous characteristics passed on to the offspring

40
Q

Define adaptation.

A

the process, resulting from natural selection, by which populations become more suited to their environment over many generations.