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GCSE Biology > B13 - reproduction fact test > Flashcards

B13 - reproduction fact test Flashcards

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1
Q

what does sexual reproduction involve

A

the fusion of male and female gametes

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2
Q

what is the female gamete in animals

A

egg cell

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3
Q

what is the male gamete in animals

A

sperm cell

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4
Q

what is the female gamete in flowering plants

A

egg cell

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5
Q

what is the male gamete in flowering plants

A

pollen

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6
Q

what does the formation of gametes involve

A

cell division called meiosis

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7
Q

why are offspring produced through sexual reproduction genetically different

A

there is a mixing of genetic information

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8
Q

what are the advantages of sexual reproduction

A
  • produces variation in the offspring
  • if the environment changes, variation gives a survival advantage by natural selection
  • natural selection can be sped up by humans in selective breeding to increase food production
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9
Q

what does asexual reproduction involve

A

only one parent and no fusion of gametes

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10
Q

why are offspring produced through asexual reproduction genetically identical

A

there is no mixing of genetic information so this lead to clones

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11
Q

how does asexual reproduction happen

A

mitosis

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12
Q

what are the advantages of asexual reproduction

A
  • only one parent needed
  • more time and energy efficient as do not need to find a mate
  • faster than sexual reproduction
  • many identical offspring can be produced when conditions are favourable
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13
Q

what is meiosis and what happens during it

A

produces gametes that have half the normal chromosome number and so when fertilisation happens the zygote has the full number of chromosomes again

  1. normal cell, 46 chromosomes
  2. DNA replicates
  3. first cell division, 46 chromosomes
  4. second cell division, number of chromosomes is halved so 23 chromosomes
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14
Q

what are the similarities between mitosis and meiosis

A
  • DNA replicates
  • there is an increase in the number of sub-cellular structures
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15
Q

what are the differences between mitosis and meiosis

A
  • mitosis produces 2 daughter cells but meiosis produces 4
  • mitosis has 1 cell division but meiosis has 2
  • mitosis produces cells with 2 of each chromosome but meiosis produces cells with one
  • mitosis produces genetically identical cells but meiosis produces genetically different cells
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16
Q

what is a diploid cell

A

contains the full number of chromosomes e.g in humans 23 pairs

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17
Q

what is a haploid cell

A

contains half the number of chromosomes e.g in humans 23 chromosomes

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18
Q

what is DNA

A

a double stranded polymer wound to form a double helix. carries the genetic code

a polymer made from 4 different types of nucleotides

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19
Q

what is a chromosome

A

a long coiled molecule of DNA that carries genetic information in the form of genes

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20
Q

what is a gene

A

a section of DNA that codes for a specific sequence of amino acids that form a protein

21
Q

what is a genome

A

the complete genetic material of an organism

22
Q

what is the importance of studying the human genome

A
  • search for genes linked to different types of disease
  • understanding and treatment of inherited disorders
  • use in tracing human migration patterns from the past
23
Q

what is an allele

A

a version of a gene

24
Q

what is a dominant allele

A

an allele that is always expressed, represented by a capital letter

25
Q

what is a recessive allele

A

an allele that i only expressed in the absence of a dominant allele, represented by a lower case letter

26
Q

what does homozygous mean

A

when someone has identical alleles of a gene e.g. ff

27
Q

what does heterozygous mean

A

when someone has 2 different alleles of a gene e.g Ff

28
Q

what is a genotype

A

an organism’s genetic composition, describes all alleles

29
Q

what is a phenotype

A

an organism’s observable characteristics, due to interactions of the genotype and the environment

30
Q

what does a nucleotide consist of

A

a common sugar and phosphate group with one of 4 different bases (A,T,C and G)

31
Q

which of the 4 bases bind to each other

A

A and T always bind
C and G always bind

32
Q

what is DNA polymer made up of

A

repeating nucleotide units
the long stands of DNA consist of alternating sugar and phosphate sections

e.g strand of DNA: TGC CCG
complimentary strand: ACG GGC

33
Q

what are proteins made from

A

chains of amino acids and are synthesised in ribosomes

34
Q

what is the code for a particular amino acid

A

a sequence of 3 bases

35
Q

what does the order of bases control

A

the order in which amino acids are assembled to produce a particular protein

36
Q

what is the process of protein synthesis

A
  1. DNA can’t leave the nucleus so a template is made (T is replaced with U) which leaves the nucleus and travels to the ribosome
  2. proteins are synthesised on ribosomes, according to the template
  3. carrier molecules bring specific amino acids to add to the growing protein chain in the correct order
  4. when the protein chain is complete, it folds up to form a unique shape
  5. this unique shape enables the proteins to do their job as enzymes, hormones or forming structures in the body such as collagen
37
Q

what is a mutation

A

a change in the DNA base sequence

38
Q

what do you need to know about mutations

A
  • they are random and occur continuously
  • most don’t alter the protein or only alter it slightly so that its appearance or function is not changed
  • a few mutations code for an altered protein with a different shape, an enzyme may no longer fit the substrate binding site or a structural protein may lose its strength
  • not all parts of DNA code for proteins, non-coding parts of DNA can switch genes on and off so variations in these areas of DNA may effect how genes are expressed
39
Q

what can a mutated gene lead to

A

an abnormal protein or no protein

40
Q

what does it mean if something is inherited in genetics

A

it is passed on from your parents

41
Q

what is hereditary a descriptive term for

A

conditions capable of being transmitted from parent to offspring through the genes

42
Q

what is polydactyly

A

a dominant condition where someone is born with extra fingers or toes

43
Q

what is cystic fibrosis

A
  • an inherited recessive condition in which the lungs and digestive system can become clogged with thick, sticky mucus.
  • can cause problems with breathing and digestion from a young age.
  • over many years, the lungs become increasingly damaged and may eventually stop working properly
44
Q

when is an individual classed as a carrier of disease

A

when they have an
allele for the disease in their genotype but it’s not expressed in their phenotype (only for recessive diseases)

45
Q

what are reasons for embryonic screening

A
  • reduces number of people suffering (ethical)
  • treating genetic disorders is expensive (economic)
  • many regulations in place so it doesn’t get out of hand (social)
46
Q

what are reasons against embryonic screening

A
  • could encourage people to pick characteristics creating designer babies (ethical)
  • expensive to carry out screening (economics)
  • may promote prejudice as it suggests those with genetic disorder are unwanted (social)
  • decisions about terminating pregnancy have to be made (social)
  • procedure can lead to miscarriage (social)
47
Q

what is gene therapy

A

the process by which normal alleles are inserted into the chromosomes of an individual who carries defective alleles e.g. those that cause a genetic disorder

48
Q

what are concerns associated with gene therapy

A

developing technology and not always successful
same concerns as embryonic screening. many people believe gene alteration is unnatural, others think it helps alleviate suffering in those with genetic disorders

GCSE Biology (49 decks)

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