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Biology > Topic 3 - DNA, inheritance & Protein Synthesis > Flashcards

Topic 3 - DNA, inheritance & Protein Synthesis Flashcards

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1
Q

The term used to describe the number of chromosomes in an egg or sperm cell is (1)

A

Haploid

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2
Q

Elk, Alces alces, are members of the deer family.
Elk mate in the autumn and their calves are born in the spring.
During the mating season males make sounds to attract females.
This type of behaviour is part of… (1)

A conditioning
B courtship
C habituation
D imprinting

A

Courtship

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3
Q

Female elk are attracted to males by the size of their antlers.
Suggest why a male elk may move away if challenged by another male with larger antlers. (1)

A

Avoid injury/don’t waste energy

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4
Q

A pregnant elk will search for a group of thick bushes in which to give birth.
Explain an advantage of this behaviour. (2)

A

Protection of female during birth (1)
From predators (1)

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5
Q

Some plants produce tannins.
Tannins are toxic. The tannins stop some herbivores from eating these plants.
Elk produce proteins in their saliva which bind to the tannins and make them inactive.
This inter-relationship is a product of co-evolution.
Describe the advantages to the elk of producing tannin-binding proteins in their saliva. (2)

A

Can eat plants which contain tannins (1)
Larger food supply (1)
Plants not consumed by other herbivores/less competition between other animals/herbivores (1)

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6
Q

The development of flower structure and insect behaviour is another example of co-evolution.
Describe how this relationship benefits the plant. (2)

A

(Flower) attracts insects (1)
Which pollinate the flower (1)
Insect - flower relationship is specific (1)

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7
Q

Sperm cells and egg cells are needed for human sexual reproduction.
Describe in detail the type of cell division that produces sperm cells. (4)

A

Divide by meiosis (1)
4 cells produced (1)
Haploid cells (1)
Cells are genetically different (1)

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8
Q

Describe the processes that take place in the formation of the fetus from a sperm cell and an egg cell. (6)

A

• fertilisation of egg by sperm • ref to fusion of nuclei
• forming diploid cell
• ref to zygote
• (zygote) divides by mitosis
• to form identical cells
• several mitotic divisions
• growth of foetus
• examples of how fetus grows eg in height, mass
• stem cells in embryo • specialisation / differentiation of (stem) cells into different cell types • examples of different cell types eg neurones, skin cells • development of fetus

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9
Q

State two differences between sexual reproduction and asexual reproduction. (2)

A

Sexual reproduction involves 2 parents/asexual reproduction only involves 1 parent/organism (1)
Sexual reproduction needs gametes/asexual reproduction doesn’t (1)
Asexual reproduction produces genetically identical organisms/sexual reproduction produces genetically different offspring (1)

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10
Q

Which row describes the sperm cell and the egg cell before fertilisation? (1)

A both diploid
B diploid sperm cell haploid egg cell
C haploid sperm cell diploid egg cell
D both haploid

A

Both haploid

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11
Q

A sperm cell contains DNA.
Describe the structure of DNA. (3)

A

(DNA is a) double helix (1)
The sides of the DNA are made from alternating sugar and phosphate molecules/sugar phosphate backbone (1)
Complementary bases (1)
Bases joined together by hydrogen bonds (1)

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12
Q

Information in a DNA strand can be transcribed to make a strand of mRNA.
Describe how this mRNA strand is then used to make proteins. (4)

A

Translation (1)
mRNA leaves the nucleus/enters the cytoplasm (1)
mRNA joins to ribosomes (1)
tRNA carries amino acids (1)
tRNA joins to mRNA (1)
Bases read as triplets/codons (1)
Amino acids are joined together to make polypeptides (1)

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13
Q

Gregor Mendel investigated the genetics of peas.
He didn’t know about genes but showed that inherited characteristics can be dominant or recessive.
Explain how Mendel used homozygous tall and homozygous short pea plants to show that the tall allele is dominant to the short allele. (2)

A

Mendel crossed homozygous tall and homozygous short pea plants to produce all tall offspring (1)
Therefore all the offspring had a heterozygous genotype with 1 tall and 1 short allele showing that the tall allele is dominant (1)

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14
Q

A strawberry plant has produced several runners, and new strawberry plantlets are growing at the end of each runner. This is asexual reproduction.
Explain why asexual reproduction in strawberries is beneficial to strawberry farmers. (2)

A

Asexual reproduction is a rapid reproduction technique allowing the production of more plants (1)
As there’s no requirement for cross pollination/higher crop yield/increased profit (1)

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15
Q

Strawberry fruits, containing seeds, are produced after a flower is fertilised.
Explain why seed production is an advantage to the strawberry plant. (2)

A

Introduces variation into the population (1)
Which allows for natural selection of fitter plants/increased chance of the population surviving (1)

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16
Q

H = Huntington’s allele
h = normal allele

F = normal allele
f = cystic fibrosis allele

Explain why, if both sets of parents are heterozygous, the chance of inheriting Huntington’s disease is greater than the chance of inheriting cystic fibrosis. (2)

A

Huntington’s disease is caused by a dominant allele/cystic fibrosis is caused by a recessive allele (1)
Only 1 allele for Huntington’s disease needs to be inherited to have the disease (1)
2 alleles need to be inherited to have CF (1)

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17
Q

A symptom of cystic fibrosis is: (1)

A mucus
B red blood cells
C stomach acid
D white blood cells

A

Mucus

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18
Q

Explain why a man with cystic fibrosis may be infertile (2)

A

Thick/sticky/more mucus (1)
Builds up in the tubes of the reproductive system (1)
(The mucus) blocks the flow of the sperm (1)

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19
Q

A = affected male (haemophilia)
B = unaffected female
Their offspring:
Unaffected male, carrier female, Unaffected male, carrier female, Unaffected male

Explain why the male offspring from A and B don’t have haemophilia (2)

A

They didn’t inherit the (haemophilia) allele (1)
(Allele is) located on X chromosome (1)
Males receive X chromosome from their mother/Y chromosome from their father (1)
B is homozygous dominant/X chromosome from B has the haemophilia allele (1)

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20
Q

Haemophilia can be treated using a blood clotting factor produced in a fermenter. The conditions inside a fermenter have to be carefully controlled. Explain why 1 named condition must be controlled in a fermenter. (2)

A

Aseptic conditions (1)
Prevents growth of unwanted organisms/contamination (1)
OR
Temperature/pH (1)
Provide optimal conditions for growth/prevents denaturing of enzymes (1)
OR
Nutrients (1)
Provide optimal conditions for growth (1)
OR
Aeration/oxygen (1)
For aerobic respiration/prevent anaerobic respiration (1)

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21
Q

State the genetic term used to describe an individual with the genotype ee for attached earlobes (1)

A

Homozygous recessive

22
Q

Cystic fibrosis is a genetic disorder that’s caused by the inheritance of 2 recessive alleles. Describe the symptoms of cystic fibrosis. (3)

A

Excess mucus produced (1)
In the lungs/pancreas/reproductive system (1)
Difficulty with breathing/digestion & absorption/infertility/infection (1)

23
Q

Variation may arise due to the geographic isolation of a specific. Explain how geographic you members of 1 species can lead to a new species involving. (3)

A

Speciation (1)
Different geographical area may have different selection pressures/environmental conditions (1)
Those individuals adapted/suited to this environment will survive and breed (1)
Adaptations/genes passed on to the offspring (1)
New species unable to breed with original (1)

24
Q

What’s the arrangement of the sugar, phosphate and base in a DNA nucleotide? (1)

A

Phosphate - sugar (pentagon) - base (rectangle)
(Circle)

25
Q

An allele starts with the DNA sequence ATGCATGTACCG.
Give the sequence of the complementary DNA sequence. (1)

A

TACGTACATGGC

26
Q

The length of one DNA nucleotide was measured at 3.3 × 10^–10 metres.
Calculate the approximate length of a gene containing 250 nucleotides in nanometres. (2)

A

3.3 × 10^–10 metres = 0.33nm (1)
0.33 x 250 = 82.5 (1)

27
Q

The DNA of an organism determines its phenotype.
White tigers are produced because of a mutation of a single allele which usually
produces the normal orange and yellow fur pigmentation.
The mutated allele is recessive.
Samba, a male white tiger, was bred with Rani. They had 3 offspring; 2 offspring have white fur and 1 has a normal fur pigmentation.
State the genotype of Rani (1)

A

Heterozygous

28
Q

Explain how 2 parents with a dominant phenotype can produce offspring expressing a recessive characteristic. (2)

A

Both parents must be heterozygous for the recessive allele (1)
So the offspring must inherit the recessive allele from each parent (1)

29
Q

Sickle cell disease is a genetic disorder caused by two recessive alleles.
An individual with sickle cell disease is said to be: (1)

A a carrier for sickle cell disease
B heterozygous
C homozygous dominant
D homozygous recessive

A

homozygous recessive

30
Q

Describe the main symptoms of sickle cell disease. (3)

A

Tired/lethargic (1)
Short of breath/problems exercising/reduced oxygen carrying capacity (1)
Swelling of hands/feet (1)
Painful/weak joints (1)
Blocked blood vessels/blood clots (1)

31
Q

Explain why the offspring produced by the first generation parents are not the same as those predicted in a Punnett square (2)

A

Punnett square would predict 50% normal, 50% carrier (1)
Actual offspring aren’t 50% carrier (1)
The probability is applied to each child not the overall offspring (1)

32
Q

Explain why it is important that individuals X, Y, and Z have pedigree analysis completed before they consider having children. (6)

X = unaffected male
Y = carrier female
Z = carrier male

A

Pedigree analysis would show the likelihood of their offspring inheriting the disorder Pedigree analysis should also be carried out on the partners of the third generation.
• X is not a carrier
• X is homozygous dominant
• and does not have sickle cell disease
• The parents of X are heterozygous / his sister has sickle cell
• so will not pass on the allele for the disease to offspring
• if his partner is a carrier
• there will be a 50% chance of the child being a carrier
• Y and Z are carriers of the sickle cell allele
• Y and Z are heterozygous
• The mother of Y has sickle cell / Y will inherit the sickle cell allele
• The parents of Z do not have sickle cell / mother is a carrier/heterozygous
• They have a 50% chance of passing the sickle cell allele onto their potential offspring
• If their partners were also carriers
• There would be a 25% chance that the offspring will have the sickle cell disease
• There would be a 50% chance that the offspring would also carry the allele for sickle cell disease

33
Q

Explain why a person with cystic fibrosis (CF) may lose body mass. (2)

A

Mucus blocks pancreatic duct/small intestine wall/digestive system (1)
Preventing enzymes being released into the small intestine (1)
Less digestion of food (1)
Less absorption (1)

34
Q

State what is meant by the term heterozygous. (1)

A

An individual who has 1 recessive allele and 1 dominant allele (1)

35
Q

Sickle cell disease is another genetic disorder caused by a recessive allele .
Explain the inheritance of sickle cell disease in a family with a heterozygous father and a homozygous recessive mother. (6)

A

• mother gametes = d, d
• father gametes = D, d
• offspring = 50% Dd, 50% dd
• probability of offspring with sickle cell disease = 50%
• probability of carrier / heterozygous = 50%
• both parents will give one allele to the possible offspring
• the father can give either the dominant or recessive allele
• the mother can only give a recessive allele
• a dominant and recessive allele will result in heterozygous offspring

36
Q

State the level of classification for both parts of the binomial name Rattus norvegicus. (2)

A

Rattus = Genus
Norvegicus = Species

37
Q

Some rats have a mutation which enables them to eat the rat poison Warfarin and survive.
Suggest how the use of Warfarin could lead to an increase in the number of rats with this mutation. (2)

A

Rats with the mutation survive to reproduce (1)
Pass on the allele which makes the offspring resistant to Warfarin (1)

38
Q

Hospitals have introduced programmes to reduce MRSA infections in patients
because antibiotics have become less effective.
The graph shows the number of males infected with MRSA during their stay in hospital.
A programme of intensive use of antiseptics in hospitals has been used since 2005.
Use the information given and your own scientific knowledge to explain the trends shown in the graph. (6)

Hill shaped graph. 1995 - 2010.

A

• MRSA is a bacterial infection
• number of cases increased from 1995 to 2006 • MRSA is resistant to antibiotics
• so MRSA infection not easy to treat
• number of cases were similar between 2005 and 2007
• antiseptics killed the bacteria
• less bacteria were transferred from person to person
• number of cases decreased from 2007
• antiseptics kill bacteria on surfaces
• causing less infections from MRSA

39
Q

A DNA molecule consists of two strands coiled to form a double helix.
Describe how the 2 strands of a DNA molecule are linked together. (2)

A

Hydrogen bonds (1)
Between (complementary) base pairs (1)

40
Q

The diagram shows part of one DNA strand.
Show the mRNA strand coded for by this DNA
strand. (2)
DNA strand: G G C T A G T T G

State the maximum number of amino acids that are coded for by this DNA strand. (1)

A

C C G A U C A A C (1)
3 (1)

41
Q

Name the structure where translation occurs. (1)

A

Ribosome

42
Q

Strawberry plants grow runners and new strawberry plants develop along the runners.
The new plants are genetically identical to the parent plant.

Name the type of cell division that results in the production of these new plants. (1)

Farmers cut the runners and sell the new plants. Suggest advantages of producing new strawberry plants in this way. (2)

A

Mitosis (1)

Same characteristics in offspring as parent plant/identical (1)
Easier to generate new plants/propagate (1)
Quicker to produce new plants (1)
Plants won’t run out, so no need to buy new seeds/plants (1)

43
Q

Some students extracted DNA from strawberries.
The diagram shows the method used:

Stage 1: grind strawberry in soapy water
Stage 2: filter mixture into a boiling tube
Stage 3: slowly pour ice cold ethanol into
the strawberry filtrate
Stage 4: remove DNA with a wire loop

A

Stage 1: to break open cells/release DNA/cell contents (1)
Stage 3: to precipitate DNA from solution/to separate DNA from other components (1)

44
Q

Describe how a section of DNA determines the structure of a protein. (4)

A

Gene coding for a protein (1)
Sequence of bases determine sequence of amino acids (1)
1 codon/triplet is 1 amino acid (1)
Several amino acids make up a protein (1)
Transcription (1)
Translation (1)

45
Q

Describe the structure of DNA, including the roles of the scientists involved in its
discovery. (6)

A

Points relating to DNA structural features:
• two strands
• double helix
• (contains) bases
• A, T, C, G • adenine / A paired with thymine / T • guanine / G paired with cytosine / C
• hydrogen bonds joining bases

Contributions from Scientists:
• X-ray (crystallography) being used
• to show helical structure
• to show diameter of molecule
• how base pairs are arranged was shown
• how strands are arranged was shown
• modelling

46
Q

Human DNA was sequenced during the Human Genome Project.
Explain how the Human Genome Project has contributed to advances in medicine. (2)

A

Genes/base sequence on human chromosome identified (1)
Identification of faulty/mutated genes (1)
People can be tested for a genetic disorder (1)
Development of gene therapy (1)
Personalised genomic medication/counselling can be given (1)

47
Q

Amino acids will be joined together during protein synthesis.
During which stage of protein synthesis will this take place? (1)

A

Translation

48
Q

Amino acids are joined together… (1)

A at the membrane
B in the mitochondria
C in the nucleus
D at the ribosome

A

Ribosome

49
Q

There are different types of white blood cell in the body. 1 type is called CD4+ T-Helper cells.
The normal range of these cells in the blood is between 5 × 108 and 1.2 × 109 cells/dm3
An AIDS patient has a CD4+ T-Helper cell count of 1.5 × 108 cells/dm3
Explain why the CD4+ count of 1.5 × 108 cells/dm3 has led to the diagnosis of AIDS. (2)

A

The CD4+ is significantly below the normal range because the HIV has destroyed the white blood cells/ CD4+ cells. (1)
So the person is more susceptible to opportunistic infections and classified as having AIDS. (1)

50
Q

Some sexually transmitted infections (STIs) can be diagnosed by testing urine samples.
These tests use monoclonal antibodies that bind to an antigen on the pathogen.
Describe how a monoclonal antibody can be developed and used to detect an STI using a urine sample. (6)

A

• isolate an antigen from the pathogen which causes the STI
• inject the antigen into a mouse/rodent collect lymphocytes producing an antibody to the STI antigen
• fuse the B-lymphocyte with a myeloma cell
• production of a hybridoma
• hybridoma produces a monoclonal antibody against the antigen of the STI
• attach the monoclonal antibody to coloured bead/indicator
• incorporate into a test strip.

51
Q

The antigens on pathogens can be proteins with a specific amino acid sequence.
Explain how the order of amino acids in a protein is determined by the sequence of the gene. (4)

A

• a single strand of messenger RNA is transcribed from the gene in the nucleus (1)
• messenger RNA molecule binds to the ribosome (1)
• the triplet code from the mRNA is matched by a complementary tRNA anticodon at the ribosome (1)
• tRNA transfers amino acids to the polypeptide chain in a specific order (1)

Biology (9 decks)

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