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Exam preparation !!!!!!!!!@!!!!!!!!!!!!!~!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Discuss the evidence for the theory that mitochondria may have evolved from free-living prokaryotes by endosymbiosis. [3 marks]

A

a. «double» membrane may have formed when engulfed
d. they have «70s» ribosomes AND can manufacture «their own» proteins
b. replicate by binary fission like free-living prokaryotes

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2
Q

Identify the stage of mitosis labelled X in the image, giving a reason. [1 mark]

A

telophase because the chromosomes/chromatids have reached the poles

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3
Q

The structure of prokaryotic cells has been investigated using electron microscopy. Draw a labelled diagram to show prokaryotic cell structure. [4 marks]

A

a. cell wall — a uniformly thick wall ✔
b. pili — hair-like structures connected to cell wall
d. «70S» ribosomes — drawn as small discrete dots not circles ✔
e. naked DNA/nucleoid — region with DNA not enclosed in membrane ✔

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4
Q

Discuss the cell theory and its limitations. [7 marks]

A

Cell Theory:
a. cell theory is the accepted explanation of life ✔

b. organisms are composed of «one or more» cells ✔
c. cells are the basic/fundamental/smallest units of life ✔
d. cells can only come from pre-existing cells ✔
e. spontaneous generation of life has been disproven ✔

Limitations:

f. striated muscle cells contain many nuclei «while most eukaryotic cells have one nucleus»
g. giant algae have complex single cell structure

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5
Q

Draw a labelled diagram to show the fluid mosaic model of the plasma membrane. [4 marks]

A

a. two correctly oriented layers of phospholipids/phospholipid bilayer shown with heads facing in opposite directions
b. phospholipids shown with two parts labelled hydrophilic/phosphate head AND hydrophobic/hydrocarbon tail
c. protein (any) shown as a globular structure embedded in one/both layers of phospholipid
d. peripheral protein, shown as globular structure at the surface of the membrane AND integral protein shown as embedded globular structures

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6
Q

Unicellular and multicellular organisms share the same functions of life. Outline four functions of life. [4 marks]

A

b. metabolism: conversion of organic molecules/chemical reactions in an organism
c. growth: increase in size/mass/number of cells within an organism
d. response/irritability/sensitivity: reactions/responsiveness to stimuli/factors
e. homeostasis: regulating/maintaining constant/stable interior environment

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7
Q

State the name of the structures labelled I and II. [1 mark]

A

I. cell wall

II. nucleus/chromatin

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8
Q

Outline the function of the structure labelled III. [2 marks]

A

a. necessary for photosynthesis/converts light energy into chemical energy
b. contains chlorophyll to absorb light

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9
Q

Describe how Pasteur’s experiments provided convincing evidence to falsify the concept of spontaneous generation [3 marks]

A

a. spontaneous generation is life appearing from nothing / from non-living / cells only come from pre-existing cells/life

b. broth/culture medium (for bacteria) (used/placed) in flasks
c. broth boiled/sterilized «in some flasks» to kill microbes

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10
Q

State the function of life in Paramecium that is carried out by: cilia. [1mark]

A

movement/locomotion

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11
Q

State the function of life in Paramecium that is carried out by: the contractile vacuole.
[1mark]

A

homeostasis

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12
Q

Discuss the advantages and disadvantages of the use of adult stem cells. [3 marks]

A

Advantages:

a. «adult stem cells» can divide «endlessly» / can differentiate
b. «adult stem cells» can be used to repair/regenerate «tissues»

Disadvantages:

i. difficult to obtain/collect/find in adult body/very few available

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13
Q

(i) State the process that divides one nucleus into two genetically identical nuclei.
(ii) Explain how the cell cycle is controlled.

[5 marks]

A

(i) mitosis

(ii)
a. cell cycle is a sequence of stages / cell cycle is G1, S, G2 and mitosis

b. (control of the cell cycle) by cyclins/cyclin
c. levels of cyclins rise (and fall)/fluctuate during the cell cycle/surge at different times/have to reach a certain concentration
d. conditions inside as well as outside the cell affect regulation

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14
Q

Outline the stages of the cell cycle.

[5 marks]

A

a. interphase is the longest phase;
b. interphase includes G1, S and G2;
c. in G1 and G2 /G phases, cell performs normal functions/protein synthesis/cell grows/organelles are replicated;
d. S/synthesis phase when the DNA replicates;
e. mitosis is when nucleus/genetic material divides;

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15
Q

Cell membranes separate aqueous environments in cells. Explain how the properties of phospholipids help to maintain the structure of cell
membranes.
[8 marks]

A

a. (labelled) phospholipid consisting of head and two tails;
b. head is glycerol and phosphate;
c. tails are fatty acid chains;
d. head hydrophilic and tails hydrophobic;

e. hydrophilic molecules/heads attracted to/soluble in
water;

f. hydrophobic molecules/tails not attracted to water but attracted to each other;
g. (properties of phospholipids leads to) formation of double layer in water;
h. stability in double layer because heads on outer edge are attracted to water

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16
Q

Milk contains lactose which some people can digest but some cannot. Explain the production of lactose-free milk.
[3 marks]

A

a. lactase added to milk / lactase immobilised;
b. lactose hydrolysed/broken down into glucose and galactose;
c. for people who are lactose intolerant/lack lactase;

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17
Q

Cellulose is the most abundant organic polymer on Earth. Describe the structure of cellulose. [3 marks]

A

a. unbranched/straight chain of glucose molecules
b. formed of beta glucose;
c. formed by condensation reactions/glycosidic bonds

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18
Q

State two structural features that differ between RNA and DNA. [2 marks]

A

a. number of strands

b. base composition

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19
Q

Water has important solvent properties. Explain these properties using an example to illustrate your answer.
[3 marks]

A

a. water molecule is polar
c. water forms hydrogen bonds with polar substances
d. positive/hydrogen side/pole of water attracted to negative ions

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20
Q

Compare and contrast cis-fatty acids and trans-fatty acids.

[2 marks]

A

a. both are unsaturated fatty acids

b. in cis-fatty acids the two H atoms are on the same side while in trans-fatty acids they are on opposite sides

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21
Q

Outline the stages in the production of mRNA by transcription.
[4 marks]

A

a. DNA is unwound/strands are separated «by RNA polymerase» ✔
b. new nucleotides attached to template strand «by RNA polymerase» ✔
d. mRNA detaches from template ✔
e. DNA rewinds ✔

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22
Q

Outline how translation depends on complementary base pairing. [3 marks]

A

a. translation converts a sequence of mRNA nucleotides to a sequence of amino acids
b. «triplets of» nucleotides «activated» tRNAs pair with complementary «triplets of» nucleotides on mRNA
c. base pairing occurs when adenine pairs with uracil and guanine pairs with cytosine

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23
Q

Describe the polymerase chain reaction (PCR), including the role of Taq DNA polymerase. [4 marks]

A

a. PCR is process by which a small sample of DNA can be amplified/copied many times
b. PCR involves repeated cycling through high and lower temperatures «to promote melting and annealing of DNA strands»
c. «mixture» is heated to high temperatures to break «hydrogen» bonds between strands of DNA/to separate the double-stranded DNA
d. Taq DNA polymerase can withstand high temperatures without denaturing

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24
Q

Draw the structure of a section of DNA showing all possible bases.
[4 marks]

A

k

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25
Q

Outline the structural and genetic characteristics of eukaryotic chromosomes. [4 marks]

A

a. linear/not circular DNA molecule
b. associated with histone proteins/nucleosomes

c. centromere joins sister chromatids «after DNA
replication»

d. telomeres at the end «of the chromosome/chromatid»

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26
Q

Outline the roles of helicase and ligase in DNA replication. [4 marks]

A

helicase:
a. unwinds/uncoils the DNA «double helix» ✔

b. breaks hydrogen bonds «between bases» ✔
c. separates the «two» strands of DNA and creates replication fork ✔

ligase:
d. seals nicks/forms a continuous «sugar-phosphate» backbone/strand ✔

27
Q

DNA has regions that do not code for proteins. State two functions of these regions. [2 marks]
1.
2.

A

c. genes for tRNA/rRNA production ✔

d. other valid function for non-coding sequence ✔

28
Q

Distinguish between the structures of DNA and RNA.

[3 marks]

A

k

29
Q

Isolated communities in rural Finland, Hungary and some of the Scottish islands have a high incidence of red-green colour blindness. Describe the inheritance of red-green colour blindness. [3 marks]

A

a. sex linked/gene is on the X chromosome ✔

b. allele «for red-green colour blindness» is
recessive/colour blindness is recessive trait/disorder ✔

c. heterozygous females are unaffected/carriers ✔

30
Q

Describe ABO blood groups as an example of codominance.

[1 mark]

A

allele IA and the allele IB are (co)dominant as they are both expressed in the heterozygote

31
Q

Describe the application of DNA profiling to determine paternity.
[5 marks]

A

a. DNA from child, mother and possible father(s) used to establish paternity;
b. (DNA profiling is done) for legal reasons / divorce / inheritance;
c. (DNA profiling is done) for personal reasons / self-esteem issues for children/fathers/parents;
d. DNA copied/amplified using PCR;
e. DNA cut using restriction enzymes;

32
Q

Explain the inheritance of colour blindness.

[8 marks]

A

a. colour blindness caused by recessive allele / colour blindness is recessive;
b. gene located on X chromosome/sex-linked;
c. Xb is allele for colour blindness and XB is allele for normal colour vision/dominant allele;
d. male has one X and one Y chromosome;
e. male has only one copy of gene(s) located on X chromosome;
f. X chromosome (in males) comes from female parent;
g. any male receiving allele from mother will express the trait;
h. XbY is genotype for colour blind male;

33
Q

Explain the process of genetically modifying bacteria.

[8 marks]

A

a. genetic modification carried out by gene transfer between species
b. genes transferred from one organism to another produce the same protein/amino acid sequence
c. due to universality of genetic code
d. mRNA for required gene extracted/identified
e. DNA copies of mRNA made using reverse transcriptase
f. PCR used (to amplify DNA to be transferred)
g. genes/DNA transferred from one species to another using a vector
h. plasmid acts as vector to transfer genes to bacteria/E. coli

34
Q

Describe the origin of eukaryotic cells according to the endosymbiotic theory. [4 marks]

A

a. mitochondria and chloroplasts are similar to prokaryotes
b. «host» cell took in another cell by endocytosis/by engulfing «in a vesicle»
c. but did not digest the cell/kept the «ingested» cell alive
d. chloroplasts and mitochondria were once independent/free-living «organisms»

35
Q

Outline natural methods of cloning in some eukaryotes.

[3 marks]

A

a. clones are genetically identical organisms
b. asexual reproduction in plants such as tubers
d. budding in yeast

36
Q

Explain benefits and risks of using genetically modified crops for the environment and also for human health.
[8 marks]

A

Environment benefits:
a. pest-resistant crops can be made

b. so less spraying of insecticides/pesticides
c. less fuel burned in management of crops
d. longer shelf-life for fruits and vegetables so less spoilage

Environment risks:
g. non-target organisms can be affected

h. genes transferred to crop plants to make them herbicide resistant could spread to wild plants making super-weeds

Health benefits:
k. nutritional value of food improved by increasing nutrient content

l. crops could be produced that lack toxins or allergens

37
Q

Draw a labelled diagram of a section of DNA showing four nucleotides. [5 marks]

A

k

38
Q

Outline a technique used for gene transfer. [5 marks]

A

a. plasmid used for gene transfer/removed from bacteria;
b. plasmid is a small/extra circle of DNA;
c. restriction enzymes/endonucleases cut/cleave DNA (of plasmid);
d. each restriction enzyme cuts at specific base sequence/creates sticky ends;
e. same (restriction) enzyme used to cut DNA with (desired) gene;

39
Q

Meiosis in humans produces cells that participate in fertilization. Outline the processes involved in meiosis.
[5 marks]

A

a. meiosis reduces a diploid cell into (four) haploid cell(s);
b. (during prophase I) homologous chromosomes pair up/synapsis;
c. chromatids (break and) recombine / crossing over
d. (metaphase I) (homologous chromosomes) at the equator of the spindle / middle of cell;
e. (anaphase I) (homologous) chromosomes separate and move to opposite poles;
f. (telophase I) chromosomes reach poles and unwind

40
Q

Following fertilization, cells in the developing embryo differentiate. Outline a technique for cloning using differentiated animal cells. [5 marks]

A

a. differentiated/somatic/diploid cells taken from donor animal/sheep udder;
b. (diploid) nucleus from donor cells removed;
c. ova/eggs cells removed from (donor) animal/female sheep;
d. (haploid) nucleus removed from eggs/ova;
e. (diploid/donor’s) nucleus is fused with/inserted into egg/ovum (to form zygote);

41
Q

Describe what is shown in a cladogram. [2 marks]

A

a. similarities/differences between organisms/species/clades ✔ mpa and mpd concern actual characteristics, not evolutionary relationships.
b. «probable» evolutionary relationships/closeness/common ancestry/phylogeny ✔ mpb concerns such relationships

42
Q

Outline how variation in organisms of the same species could lead to natural selection. [3 marks]

A

a. survival of the better adapted/fittest ✔
b. more reproduction of better adapted/fittest/individuals with favorable variations ✔
c. genes for favorable variations/adaptations passed on to offspring ✔ Accept answers in the converse.

43
Q

Explain how natural selection can lead to speciation.

[7 marks]

A

a. natural selection is caused by selection pressures in the environment
b. natural selection requires that variation exists within a species ✔
c. variation arises randomly due to mutation
d. over-production of offspring promotes selection
e. well adapted individuals/individuals with best variations survive to reproduce/survival of fittest ✔
f. «frequency of» genes/alleles conferring an advantage are selected for
g. genetic divergence/difference increases

44
Q

Outline the types of evidence that can be used to place a species in a particular clade. [3 marks]

A

a. a clade is a group of organisms that have evolved from a common ancestor ✔
b. identify the base sequences of a gene ✔

45
Q

Some plant families, such as the figwort family, have been reclassified on the basis of evidence from cladistics. Explain the methods that have been used recently to reclassify groups of plants.
[3 marks]

A

a. «previous» classification used to be based on the phenotype ✔
b. «modern cladistics uses» RNA/DNA nucleotide homology ✔
c. DNA mutation occurs at a relatively constant rate allowing estimation of when species diverged ✔

46
Q

The human hand is an example of adaptive radiation. Outline adaptive radiation. [5 marks]

A

a. «happens in a group of species that» evolve from a common ancestor ✔
b. evolution «of a structure» in different ways ✔
c. for different functions ✔
d. common features remain «despite the differences» ✔
e. homologous structures are evidence «of adaptive radiation»

47
Q

State one reason that viruses are not classified as living organisms. [1 mark]

A

b. cannot reproduce by themselves

48
Q

State the plant phylum which is characterised by the absence of vascular tissue. [1 mark]

A

bryophyta

49
Q

C. nemoralis (pictured below) is a mollusc. Identify two external features that distinguish this snail from an arthropod. [2 marks]

A

a. unsegmented body (whereas arthropods are segmented)

b. shell (versus exoskeleton in arthropods)

50
Q

Describe the evolution of antibiotic resistance in bacteria. [4 marks]

A

a. problem results from excessive use of antibiotics by doctors
b. natural variation exists in any population of bacteria making some resistant to a specific antibiotic
c. variation arises from mutation
d. antibiotic kills all bacteria except those that are resistant

51
Q

Outline how the bird, bat and human forelimb can be used to illustrate the concept of homologous structures.
[2 marks]

A

a. (homologous structures have evolved) from a common ancestor
b. divergent evolution/adaptive radiation

52
Q

State two characteristics of plants from the phylum you stated in (a)(i). [2 marks]

A

a. have roots, stem and leaves

d. produce spores/sporangia

53
Q

Describe one type of molecular-based evidence to identify members of a clade. [2 marks]

A

a. base sequences of a gene/DNA/mtDNA

b. species with the most similarities «in base sequence have recently diverged/a common ancestor

54
Q

Outline the process of speciation. [4 marks]

A

a. speciation is the splitting of a species «into two species»
b. reproductive isolation/lack of interbreeding
c. isolation due to geography/«reproductive» behavior/«reproductive» timing
d. polyploidy can cause isolation

55
Q

Describe, using one example, how homologous structures provide evidence for evolution. [4 marks]

A

a. similar structure but different function «in homologous structures»
b. pentadactyl limbs
c. similar bone structure «in pentadactyl limbs» but different functions
e. suggests a common ancestor «and evolutionary divergence»

56
Q

Describe how variation contributes to evolution by natural selection.
[3 marks]

A

a. (variation is) different phenotypes/differences between individuals in a population/species
b. struggle/competition for survival
c. some individuals have advantageous characteristics/are better adapted/have greater chance of survival/reproduction (than others)

57
Q

Outline what is required for speciation to occur.

[3 marks]

A

a. divided species/gene pool / part of species/gene pool becomes separated / species splits into separate populations
b. reproductive isolation / lack of interbreeding
c. may be due temporal/behavioural/geographic isolation

58
Q

State the name of the domain to which these organisms belong. [1 mark]

A

Eukaryotes

59
Q

Outline how fossil records can provide evidence for evolution. [2 marks]

A

a. the sequence in which fossils appear matches the expected sequence of evolution;
b. comparisons with fossils and living organisms (morphology) shows change in characteristics from an ancestral form

60
Q

Explain how evolution may happen in response to an environmental change.
[8 marks]

A

a. (genetic) variation in population;
b. (variation is) due to mutation / sexual reproduction;

d. more offspring are produced than can survive /
populations over-populate;

e. competition / struggle for resources/survival;
g. survival of fittest/best adapted (to the changed environment)/those with beneficial adaptations / converse;
i. favourable genes/alleles passed on / best adapted reproduce (more) / converse;
k. alleles for adaptations to the changed environment increase in the population;
m. evolution by natural selection;

61
Q

Describe cell respiration in terms of metabolism. [2 marks]

A

a. «cell respiration is metabolism because» enzymes control the reactions
b. energy is released from complex molecules «to make ATP»

62
Q

Explain how the process of evolution occurs. [8 marks]

A

Evolution is «cumulative» change in population/species over time

A population has variations amongst the individuals

Due to meiosis

Due to mutations

Certain variations give an advantage to some organisms over others in certain environments

Populations/species produce more offspring than the environment can support

Individuals of the species compete for the same resources

The better-adapted organisms tend to survive and reproduce

63
Q

Explain how ATP is generated in

animal cells. [8 marks]

A

a. ATP is a form of energy currency/immediately available for use;
b. ATP is generated in cells by cell respiration (from organic compounds);
c. aerobic (cell respiration) requires oxygen;
d. anaerobic (cell respiration) does not require oxygen;
e. glycolysis breaks down glucose into pyruvate;
f. glycolysis occurs in cytoplasm;
g. (by glycolysis) a small amount of ATP is released;

h. ADP changes into ATP with the addition of a phosphate
group/phosphoric acid / accept as chemical equation;

Biology (6 decks)

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