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2024-2026 Biology > Cells & Studying cells > Flashcards

Cells & Studying cells Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is the function of Cell surface membrane? [2]

A
  • Made of a Phospholipid Bi-layer;
  • Controls what enters the cell/ is selectively permeable;
  • Can be folded to increase surface area;
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2
Q

What is the function of the Nucleus? [2]

A
  • Contains genetic material / DNA;
  • Controls cell activity;
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3
Q

Describe the structure and function of the nucleus. [5]

A

Structure

  • Nuclear envelope and pores OR Double membrane and pores;
  • Chromosomes/chromatin OR DNA with histones;
  • Nucleolus/nucleoli;

Function
* (Holds/stores) genetic information/material for polypeptides (production) OR (Is) code for polypeptides;
* DNA replication (occurs);
* Production of mRNA/tRNA OR Transcription (occurs);
* Production of rRNA/ribosomes;

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4
Q

What is the function of the Mitochondria? [2]

A
  • Site of aerobic respiration;
  • ATP production;
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5
Q

What is the function of Chloroplasts? [2]

A
  • Contain thylakoids, stacked into Granum;
  • Site of photosynthesis;
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6
Q

What is the function of Golgi Apparatus? [2]

A
  • Modifies/packages/sorts proteins;
  • Produces vesicles;
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7
Q

What is the function of Lysosomes? [2]

A
  • Contains hydrolytic (digestive) enzymes;
  • Digests worn out organelles/autolysis;
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8
Q

What is the function of the Ribsosomes?

A
  • Site of Protein synthesis;
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9
Q

What is the function of the Rough Endoplasmic reticulum? [3]

A
  • Encrusted in Ribosomes;
  • Site of protein synthesis;
  • Transports and stores protein within the cell
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10
Q

What is the function of the Smooth Endoplasmic Reticulum?

A

Site of lipid synthesis;

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11
Q

What is the function of Cell Wall (plant)? [3]

A
  • Provides rigid shape / structure;
  • Stops osmotic lysis;
  • Made of cellulose
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12
Q

What is the function of the cell (permanent) vacuole (plants)?

A
  • Stores sugars/minerals/pigments
  • Support
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13
Q

Eukaryotic cells produce and release proteins. Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells. [5]

A
  • DNA in nucleus is genetic code (for protein);
  • Ribosomes/rough endoplasmic reticulum produce (protein);
  • Mitochondria produce ATP (for protein synthesis);
  • Golgi apparatus package/modify; OR Carbohydrate added/glycoprotein produced by Golgi apparatus;
  • Vesicles transport OR Rough endoplasmic reticulum transports;
  • (Vesicles) fuse with cell(-surface) membrane;
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14
Q

What is the function of Cell Wall (bacteria)? [3]

A
  • Provides rigid shape / structure;
  • Stops osmotic lysis;
  • Contains murein / peptidoglycan (glycoprotein)
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15
Q

What is the function of a Plasmid? [2]

A
  • Circular DNA;
  • Contains antibiotic resistance genes;
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16
Q

What is the function of a Capsule?
Prokaryotes only

A
  • Protects cell from (host) immune systems;
  • Aids bacteria sticking together /adhering to surfaces;
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17
Q

What is the function of a Flagellum/flagella ?

A

Allows movement/propulsion;

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18
Q

Compare and contrast Eukaryotic and Prokaryotic DNA [5]

A

Comparisons
* Nucleotide structure is identical;
* Nucleotides joined by phosphodiester bond;
* OR Deoxyribose joined to phosphate (in sugar, phosphate backbone);
* DNA in mitochondria / chloroplasts same / similar (structure) to DNA in prokaryotes;

Contrasts
* Eukaryotic DNA is longer;
* Eukaryotic DNA contain introns, prokaryotic DNA does not;
* Eukaryotic DNA is linear, prokaryotic DNA is circular;
* Eukaryotic DNA is associated with / bound to protein / histones, prokaryotic DNA is not;

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19
Q

Compare and contrast Nuclear DNA and Chloroplast / Mitochondrial DNA [5]

A

Comparisons
* Nucleotide structure is identical;
* Nucleotides joined by phosphodiester bond;
* OR Deoxyribose joined to phosphate (in sugar, phosphate backbone);

Contrasts
DNA within the nucleus:
* Is longer ;
* Contain introns, Chloroplast/MT DNA does not;
* Is linear, Chloroplast/MT DNA is circular;
* DNA is associated with / bound to protein / histones, Chloroplast/MT DNA is not;

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20
Q

State three differences between DNA in the nucleus of a plant cell and DNA in a prokaryotic cell. [3]

A

Plant v prokaryote

  • (Associated with) histones/proteins v no histones/proteins;
  • Linear v circular;
  • No plasmids v plasmids;
  • Introns v no introns;
  • Long(er) v short(er);
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21
Q

The structure of a cholera bacterium is different from the structure of an epithelial cell from the small intestine.

Describe how the structure of a cholera bacterium is different. [5]

A
  1. Cholera bacterium is prokaryote;
  2. Does not have a nucleus/nuclear envelope/ has DNA free in cytoplasm/has loop of DNA;

3 and 4 Any two from: [No membrane-bound organelles/no mitochondria / no golgi/no endoplasmic reticulum];
5 70s ribosomes only;
6 and 7 Any two from [Capsule/flagellum/plasmid / cell wall

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22
Q

Where are 70s ribosomes found? [3]

A
  • Prokaryotes
  • Mitochondia
  • Chloroplasts
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23
Q

Name two structures found in all bacteria that are not found in plant cells. [2]

A
  • Circular DNA (molecule in cytoplasm);
  • Murein cell wall OR Peptidoglycan cell wall OR Glycoprotein cell wall;
  • Small(er)/70s ribosomes (in cytoplasm);
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24
Q

Outline the similarities in, and the differences between, the structures of chloroplasts and mitochondria. [5]

A

Similarities

  1. Double membrane;
  2. Both contain (circular) DNA;
  3. Both contain ribosomes;

Differences

  1. Thylakoids/lamellae/grana v cristae;
  2. Stroma v matrix;
  3. Pigments v no pigments;
    Accept ‘chlorophyll v no chlorophyll’
  4. Starch grains v no starch grains;
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25
Q

Give the three structural features found in all virus particles and describe the function of one of these features. [2]

A
  1. Genetic material, capsid and attachment protein;
  2. Genetic material codes for (viral) protein
    OR
    Capsid protects the genetic material/RNA/DNA
    OR
    Attachment protein bind to receptors (on cell);
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26
Q

Explain why viruses are described as acellular and non-living. [2]

A
  1. (Acellular) no cell(-surface) membrane
    OR Not made of cells;

Accept have no organelles/cytoplasm

  1. (Non-living) have no metabolism/metabolic reactions;
    OR Cannot (independently) move/respire/replicate/ excrete
    OR (Have) no nutrition;
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27
Q

Define genome and proteome. [2]

A

(Genome)

  1. Complete set of genes in a cell
    OR (All) the DNA in a cell
    OR (All) the genes/alleles/genetic material in a cell
    OR The total number of DNA bases in a cell;

Reject ‘all the DNA/genes within a species/population’

(Proteome)

  1. (Full) range of proteins that a cell can produce
    OR (Full) range of proteins coded for by the cell’s DNA/genome;
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28
Q

Below are four statements about the structure of prokaryotic cells.

  1. No prokaryotic cell has DNA that is associated with proteins.
  2. No prokaryotic cell has membrane-bound organelles.
  3. All prokaryotic cells have one or more flagella.
  4. All prokaryotic cells have smaller ribosomes than eukaryotic cells.

Which statements about the structure of prokaryotic cells are correct?

A

statements 1, 2 and 4

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29
Q

What is a virus?

A
  • Acellular and non living
  • Consist of genetic material, a capsid and attachment proteins.
30
Q

The resolution of an image obtained using an electron microscope is higher than the resolution of an image obtained using an optical microscope.

Explain why.

A
  • Shorter wavelength between electrons

OR

  • Longer wavelength in light (rays);
31
Q

Scientists use optical microscopes and transmission electron microscopes to investigate cell structure.

Explain the advantages and limitations of using a TEM to investigate cell structure. [6]

A

Advantages:
* Small objects can be seen;
* TEM has high resolution;
* Electron wavelength is shorter;

Limitations:
* Cannot look at living cells;
* Must be in a vacuum;
* Must cut section / thin specimen;
* Preparation may create artefact;

32
Q

Give one advantage of using a TEM rather than a SEM.

A
  • Higher resolution;
    higher (maximum) magnification / higher detail (of image);
    OR
  • Allows internal details / structures within (cells) to be seen / cross section to be taken;
33
Q

Give one advantage of using a SEM rather than a TEM.

A
  • Thin sections do not need to be prepared / shows surface of specimen / can have 3-D images;
34
Q

Scientists isolated mitochondria from liver cells. They broke the cells open in an ice-cold, buffered isotonic solution.

Explain why the solution was:
a) Isotonic
b) Ice cold
c) buffered

[3]

A

a) Isotonic
* Prevents osmosis / no (net) movement of water So organelle/named organelle does not burst/shrivel;
b) Ice cold
* Reduce/prevent enzyme activity so organelles are not digested / damaged;
c) buffered
* Maintain a constant pH so proteins do not denature;

35
Q

Describe and explain how cell fractionation and centrifugation can be used to isolate mitochondria from a suspension of animal cells. [5]

A
  • Cell homogenisation to break open cells and release organelles;
  • Filter to remove (large) debris/whole cells;
  • Use isotonic solution to prevent osmotic damage to mitochondria / organelles;
  • Keep cold to prevent/reduce damage to organelles by enzyme;
  • Use buffer to maintain pH and prevent protein/enzyme denaturation;
  • Use differential Centrifuge (at high speed/1000 g) to separate nuclei / cell fragments / most dense organelles;
  • Re-spin (supernatant / after nuclei/pellet removed) at higher speed to get mitochondria in pellet/at bottom;
  • Observe pellet with a microscope to identify mitochondria;
36
Q

What is a homologous pair of chromosomes?

A

2 chromosomes that have:

Same genes,

Same location

37
Q

Describe the features of Prophase

A
  • Nuclear membrane begins to breakdown;
  • Centrioles move to poles of the cell;
  • Chromatin supercoils and condense into chromosomes around HISTONES;
  • Each chomosome consists of two identical sister chromatids joined by a centromere;
38
Q

Describe the features of Metaphase

A
  • Spidle fibres form;
  • Spindle fibres attach to the centromere of chromosomes;
  • Chromosomes align at the equator of the cell;
39
Q

Describe the features of Anaphase

A
  • Spindle fibres shorten and centromere splits;
  • Sister chromatids are separated;
  • Chromatids pulled to opposite poles of the cell;
  • Chromatids are in a V shape formation;
40
Q

Describe the features of Telophase

A
  • Nuclear membrane begins to reform;
  • Chromosomes unwind/ uncoil / become longer.
41
Q

State the stages of the cell cycle

A

Interphase (G1-S-G2)
Prophase
Metaphase
Anaphase
Telophase
(Cytokinesis)

42
Q

In which phase of the cell cycle does DNA mass double?

A

S phase of Interphase

43
Q

Define a chromosome

A

A chromosome is an independent DNA molecule which has been supercoiled into a condensed form.

Contains many genes

44
Q

What is a diploid cell?

A

A cell that has 2n chromosomes

A somatic cell

45
Q

What is a haploid cell?

A

A (gamete) cell that has n chromosomes.

46
Q

Which cells divide by mitosis?

A

Stem cells (only)

47
Q

Why is MITOSIS important? [3]

A
  • Increasing cell numbers and growth of an organism
  • Repair of damaged tissues (not cells)
  • Replacement of worn out / dead cells
48
Q

Describe the appearance and behaviour of chromosomes during mitosis: [5]

A
  1. During prophase, chromosomes supercoil and condense to become visible;
  2. Chromosomes appear as 2 identical sister chromatids joined by a centromere;
  3. During metaphase chromosomes line up on the equator of the cell;
  4. Chromosomes attach to the spindle fibres;
  5. By their centromeres;
  6. During anaphase, the centromere splits;
  7. Sister chromatids are pulled to opposite poles of the cell making a V shape;
  8. During telophase, chromatids uncoil and become thinner;
49
Q

Define allele

A

Different version of the same gene

50
Q

Define ‘Gene’

A

Section of DNA base sequences on a chromosome coding for one specific polypeptide

51
Q

Define Sister chromatid

A

One of the two strands of a replicated chromosome that are joined together by a single centromere prior to cell division

52
Q

What is a tumour? [2]

A
  • Mass of cells/tissue OR Abnormal cells/tissue;
  • Uncontrolled mitosis/ uncontrolled rapid cell division;
53
Q

Describe how you would determine a reliable mitotic index (MI) from tissue observed with an optical microscope.

Do not include details of how you would prepare the tissue observed with an optical microscope. [3]

A
  • Count cells in mitosis (visible chromosomes) in field of view;
  • Divide this by total number of cells in field of view;
  • Repeat many/at least 5 times

OR

  • Select (fields of view) at random;
54
Q

Describe and explain what the student should have done when counting cells to make sure that the mitotic index he obtained for this root tip was accurate. [2]

A

Description; Explanation;
E.g,
* Examine large number of fields of view / many cells;
* To ensure representative sample;

OR
* Repeat count;
* To ensure figures are correct;

OR

  • Method to deal with part cells shown at edge /count only whole cells;
  • To standardise counting;
55
Q

Describe and explain what the student should have done when counting cells to make sure that the mitotic index he obtained for this root tip was accurate.
Describe binary fission in bacteria. [3]

A
  • Replication of (circular) DNA;
  • Replication of plasmids;
  • Division of cytoplasm (to produce 2 daughter cells);
56
Q

Describe Viral replication [5]

A
  • Attachment proteins attach to receptors
  • (viral) nucleic acid enters cell
  • Nucleci acid replicated in cell OR Reverse transcriptase makes DNA from RNA
  • Cell produces (viral) protein/capsid/enzymes
  • Virus assembled and released (from cell)
57
Q

Describe how the process of meiosis results in haploid cells. Do not include descriptions of how genetic variation is produced in meiosis. [5]

A
  • DNA replication (during late interphase);
  • Two nuclear divisions;
  • Separation of homologous chromosomes (in first division);
  • Separation of (sister) chromatids (in second division);
  • Produces 4 (haploid) cells/nuclei;
58
Q

Meiosis results in cells that have the haploid number of chromosomes and show genetic variation. Explain how. [7]

A
  • Homologous chromosomes pair up;
  • maternal and paternal chromosomes are arranged in any order;
  • Independent segregation (RANDOM);
  • Crossing over (RARE);
  • (Equal) Portions of chromatids are swapped between chromosomes;
  • Produces new combination of alleles;
  • Chromatids separated at meiosis II/ later;
59
Q

Describe the process of crossing over and explain how it increases genetic diversity. [4]

A
  • Homologous pairs of chromosomes associate / form a bivalent;
  • Chiasma(ta) form;
  • (Equal) lengths of (non-sister) chromatids / alleles are exchanged;
  • Producing new combinations of alleles;
60
Q

Give two differences between mitosis and meiosis. [2]

A

Mitosis given first
* One division, two divisions in meiosis;
* (Daughter) cells genetically identical, daughter cells genetically different in meiosis;
* Two cells produced, (usually) four cells produced in meiosis;
* Diploid to diploid/haploid to haploid, diploid to haploid in meiosis;
* Separation of homologous chromosomes only in meiosis;
* Crossing over only in meiosis;
* Independent segregation only in meiosis;

61
Q
A

6

62
Q

Contrast how an optical microscope and a transmission electron microscope work and contrast the limitations of their use when studying cells. [6]

A
  1. TEM use electrons and optical use light;
  2. TEM allows a greater resolution;
  3. (So with TEM) smaller organelles / named cell structure can be observed OR greater detail in organelles / named cell structure can be observed;
  4. TEM view only dead / dehydrated specimens and optical (can) view live specimens;
  5. TEM does not show colour and optical (can);
  6. TEM requires thinner specimens;
  7. TEM requires a more complex/time consuming preparation;
  8. TEM focuses using magnets and optical uses (glass) lenses;
63
Q
A

A, D, C, E, B;

64
Q

Name the stage of the cell cycle

A

Anaphase

65
Q

Name the stage of the cell cycle

A

Prophase

66
Q

Name the stage of the cell cycle

A

Metaphase

67
Q

Name the stage of the cell cycle

A

Telophase

68
Q

Name the stage of the cell cycle

A

Anaphase 2

Meiosis

69
Q

There are 150 cells in the field of view. (Microscope image)

How many cells have visible chromosomes if the mitotic index is 0.36?

A

150 x 0.36 = 54

70
Q

Human papilloma virus infects cells that are no longer dividing. The human papilloma virus genome contains genes that code for proteins that cause human cells to restart their cell cycles.

Human papilloma virus infection can cause cancer.

Explain why

A

Uncontrolled cell cycle/division/mitosis;

2024-2026 Biology (5 decks)

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