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Unit 4 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

How is the structure of DNA related to function (7)

A
  1. Stable due to numerous hydrogen bonds so can be passed on from generation to generation
  2. Weak hydrogen bonds between strands are easily broken for DNA replication or protein synthesis
  3. Large so can carry a lot of genetic information
  4. Base pairs are contained within the helix and held in place by the strong sugar-phosphate backbone
  5. Complementary base pairs allow the synthesis of an identical daughter molecule
  6. 2 Strands so both can act as templates
  7. Helical shape means that it can be coiled so compact for storage
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2
Q

Describe the difference between degenerate and Non-overlapping (2)

A

Degenerate: More than one base triplet for each amino acid.
Non-overlapping: Each base is part of only 1 triplet

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3
Q

Compare DNA and mRNA (6)

A
  1. DNA is double stranded, mRNA is single stranded
  2. DNA is long, mRNA is short
  3. Thymine in DNA, Uracil in mRNA
  4. Deoxyribose in DNA, Ribose in mRNA
  5. DNA has base pairing, mRNA does not
  6. DNA has introns, mRNA doesn’t
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4
Q

Comparing mRNA and tRNA (3)

A
  1. mRNA is longer
  2. mRNA is a straight but tRNA is a folded molecule
  3. mRNA contains hydrogen bonds but tRNA has hydrogen bonds
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5
Q

Which two molecules are ribosomes made from? (2)

A
  1. One of RNA
  2. One of protein
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6
Q

Define the term exon?

A

Base sequence coding for polypeptide

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7
Q

Name the proteins associated with DNA

A

Histone

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8
Q

Differences between Eukaryotic DNA and Prokaryotic DNA (5)

A
  1. Associated with Histones v No Histones
  2. Linear v Circular
  3. No plasmids v plasmids
  4. Introns v No introns
  5. Longer v Shorter
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9
Q

Describe transcription (7)

A
  1. DNA strands separate by breaking hydrogen bonds
  2. Only one of the strands is used as a template
  3. Complementary base pairing, so A to U, A to T, C to G
  4. Nucleotides joined by RNA polymerase
  5. Forms phosphodiester bonds
  6. Pre-mRNA formed
  7. Splicing to form mRNA
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10
Q

Describe Translation (7)

A
  1. mRNA binds to ribosome
  2. Ribosome moves to start codon
  3. Idea of two codons
  4. tRNA with anticodons bind to codon on mRNA
  5. tRNA brings specific amino acid
  6. mRNA moves along to the next door
  7. Formation of peptide bond between amino acids
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11
Q

Role of Ribosome in Translation (5)

A
  1. mRNA binds to ribosome
  2. Idea of two codons
  3. tRNA with anticodons bind
  4. Formation of peptide bond between amino acids
  5. Moves along mRNA to next codon
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12
Q

Role of tRNA in Translation (4)

A
  1. Anticodon complementary to codon
  2. Specific amino acid
  3. Carried to ribosome
  4. Correct sequence of amino acids along polypeptide
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13
Q

Describe how a phosphodiester bond is formed between two nucleotides within a DNA molecule

A
  1. Condensation reaction
  2. Between phosphate and deoxyribose
  3. Catalysed by DNA Polymerase
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14
Q

What is a gene

A

A sequence of DNA nucleotides that codes for a polypeptide

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15
Q

The genome is…

A

Complete set of genes in a cell

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16
Q

The proteome is…

A

The full range of different proteins that a cell is able to produce

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17
Q

Causes of Variation in Meiosis (6)

A
  1. Homologous chromosomes pair up
  2. Chiasmata formed
  3. Independent segregation
  4. Maternal and paternal chromosomes are re-shuffled in any combination
  5. Crossing over leads to exchange of parts of chromatids
  6. Both create new combinations of alleles
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18
Q

Process of Crossing Over in Meiosis (4)

A
  1. Homologous pairs of chromosomes associate
  2. Chiasmata form
  3. Lengths of chromatids are exchanged
  4. Producing new combinations of alleles
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19
Q

Describe how the process of meiosis results in haploid cells

A
  1. DNA replication creates two identical chromatids
  2. Two nuclear divisions
  3. Homologous pairs separated
  4. Sister chromatids separated
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20
Q

Define Mutation

A

A change in the base sequence of DNA, results in a new allele

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21
Q

What is meant by the degenerate code?

A

More than one codon codes for a single amino acid

22
Q

How does mutation cause change in enzyme function? (3)

A
  1. Change in amino acid
  2. Change in hydrogen bonds so alters tertiary structure
  3. Substrate not complementary so no enzyme-substrate complexes form
23
Q

How does mutation cause change in protein structure? (4)

A
  1. Change in DNA base
  2. Change in amino acid sequence
  3. Alters position of hydrogen bonds
  4. Change in tertiary structure
24
Q

Mutation leading to evolutionary changes (5)

A
  1. Mutations change base sequence
  2. Change in amino acid sequence
  3. Mutations build up over time
  4. Fewer mutations in closely related species
  5. Closely related species have recent common ancestor
25
Q

Define the term mutagenic agent

A

A factor that increases the rate of mutations

26
Q

Name ways which increase genetic variation in a population (3)

A
  1. Mutation
  2. Meiosis - crossing over and independent segregation
  3. Random fertilisation
27
Q

Define how a mutation can have a positive effect on an individual and no effect on a individual

A

No effect:
1. Genetic code is degenerate
2. Mutation is in an intron
3. Creates a recessive allele which does not affect phenotype
Positive effect:
1. New allele increases chance of survival

28
Q

Describe how mRNA is formed by transcription in eukaryotes (5)

A
  1. Hydrogen bonds break
  2. Only one DNA strand acts as a template
  3. RNA nucleotides align by complementary base pairing
  4. Uracil base pairs with adenine
  5. RNA polymerase joins adjacent RNA nucleotides
  6. By phosphodiester bonds
  7. Pre-mRNA is spliced to from mRNA
29
Q

Describe how polypeptide is formed by translation of mRNA (6)

A
  1. mRNA attaches to ribosomes
  2. tRNA anticodons bind complementary mRNA codons
  3. tRNA brings a specific amino acid
  4. Amino acids join by peptide bonds
  5. With the use of ATP
  6. tRNA released
  7. The ribosome moves along the mRNA to form the polypeptide
30
Q

Define Genetic Diversity

A

The number of different alleles of genes in a population

31
Q

Describe how a student made a 1 in 10 dilution and then used this to make a 1 in 1000 dilution of the original liquid culture of bacteria. (3)

A
  1. 1 Part bacterial culture to 9 parts water
  2. Then mix
  3. Repeat using 9 parts fresh liquid and 1 part of the 10-1 dilution to make 10-2 dilution then a 10-3 dilution
32
Q

Why would a 1 in 10 dilution not be appropriate to use to determine cell numbers? (2)

A
  1. Count unlikely to be reliable
  2. Because too many cells/ could be overlap
33
Q

Explain how the use of antibiotics has led to antibiotic-resistant strains of bacteria? (4)

A
  1. Some bacteria have alleles for resistance
  2. Exposure to antibiotics creates a selection pressure
  3. Antibiotics kill bacteria that are not resistant
  4. Resistance strains survive and reproduce
34
Q

Describe the aseptic techniques used to transfer bacterial culture onto an agar plate (5)

A
  1. Use sterile pipette
  2. Flame top of the bottle
  3. Lift lid of agar plate at an angle
  4. Use sterile spreader
  5. Place pipette onto disinfectant
35
Q

Describe the principles of natural selection in the evolution of a population (4)

A
  1. Random mutation can result in new alleles of a gene
  2. Advantageous allele benefits its possessor leading to increased reproductive success
  3. Advantageous allele is inherited by offspring
  4. Over many generations, advantageous allele increases in frequency in population
36
Q

Define Species

A

Can interbreed to produce fertile offspring

37
Q

Give the taxonomic levels of classification

A

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

38
Q

Describe how genetic diversity between species that can be measured (4)

A
  1. Comparing observable characteristics
  2. Comparing base sequences of DNA
  3. Comparing Base sequences of mRNA
  4. Comparing Amino Acid sequences
39
Q

Classification is hierarchical, what does this mean? (1)

A

Smaller groups are placed within larger groups, with no overlap between groups

40
Q

Which two taxa make up and organisms binomial name? (1)

A

It’s genus and species

41
Q

Explain what is meant by a phylogenetic group? (1)

A

When they are grouped based on their evolutionary links to a common ancestor

42
Q

The importance of Courtship behaviour (3)

A
  1. Enables male/female to recognise the other sex
  2. Enables recognition of it’s own species
  3. Synchronises mating behaviour
43
Q

How Courtship behaviour increases the probability of mating (4)

A
  1. Attracts mate of the same species
  2. Indication of sexual maturity
  3. Stimulates the release of gametes
  4. Formation of a bond between two organisms
44
Q

What is species richness (1)

A

A measure of the number of different species in a community

45
Q

Why is calculation of index of diversity more reliable than species richness?

A
  1. Index of diversity also measures abundance of each species
  2. So useful because may be many of some species
46
Q

Suggest one reason the scientists used biomass instead of the number of individuals of each plant species when collecting data to measure diversity (2)

A
  1. Individual organisms could not be identified
  2. Too small to count individuals
47
Q

Outline a method the ecologists could have used to determine the plant species richness at one site (3)

A
  1. A method of selecting sampling sites at random e.g. random number generator
  2. Use of quadrat
  3. Identify plant species at each quadrat
48
Q

Pros and Cons of a farmer when planting hedges (5)

A

Pros:
1. Greater biodiversity, so increase in predators of pests
2. Increase in predators of pests so more yield
3. Increase in pollinators so more yield
Cons:
1. Reduced land are for crop growth
2. Greater biodiversity so increase pest population
3. Increase pest population so less yield
4. Increase competition so less yield

49
Q

Suggest one ethical argument for maintaining biodiversity (1)

A

Prevent extinction/loss of habitats

50
Q

Suggest one ethical argument for maintaining biodiversity (4)

A
  1. Medical uses of plants
  2. Tourism
  3. Agriculture
  4. Saving forest communities

Biology Flash Cards (8 decks)

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