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Biology > Cells > Flashcards

Cells Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Which of the following is the correct sequence of the four phases of mitosis?

A

Prophase, metaphase, anaphase, telophase

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2
Q

How did Pasteur’s experiment with sterile broth in open flasks demonstrate the principle
that cells only come from pre-existing cells?

A

By demonstrating that sterile broth would not ferment in contact with air alone.

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3
Q

Emergent properties are found in some biological systems. Which of the following
properties is necessary for emergent properties to occur?

A

Cells or tissues interact to function as a unit

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4
Q

Which of the following organelles are surrounded by a single membrane?

A

Rough endoplasmic reticulum

Lysosome

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5
Q

Which of the following are properties of cholesterol found in plasma membranes?

A

Reduces permeability of the membrane to hydrophilic ions

It is amphipathic

Reduces fluidity of the membrane

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6
Q

Which of the following are properties of phospholipids?

A

I They have a hydrophilic phosphate head
II They form a bilayer in water
III They are amphipathic
IV They have a hydrophobic fatty acid region

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7
Q

The medium in which a donor organ for transplant is bathed in an isotonic medium, a
solution of the same concentration as the cell cytoplasm. Why?

A

The organ must not lose or gain water

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8
Q

Which of the following can cause the formation of a primary tumour, or cancer?

A

I Oncogenes
II Mutagens

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9
Q

Which of the following events happens during mitosis in a plant cell?

A

Condensation of chromosomes (Occurs by supercoiling in prophase).

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10
Q

Which statement best describes the movement of water molecules in osmosis?

A

From a dilute to a more concentrated solution across a membrane

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11
Q

Outline how the mitotic index can be used in the diagnosis of cancer?

A

Mitotic index is a measure for how fast the cells are dividing (also known as proliferation) A high mitotic index means that the cells might be cancerous;
Mitotic Index is defined as the ratio between the number of cells actively dividing (in mitosis) and the total number of cells / a low mitotic index means that the cells are dividing slowly.
Mitotic index has been shown to be a strong predictor of / to correlate to survival / prognosis / treatment success in (some) cancers.

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12
Q

List two sources of stem cells that can be used in therapeutic treatment.

A

• The patient’s own cells / tissues / donated tissues from another person;
• The foetal umbilical cord (blood);
• Early-stage embryos (specially created);

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13
Q
  1. Outline two similarities between the structure of prokaryote cells and eukaryote cells.
A

Both cells have;
• plasma membrane
• ribosomes (although they are 70s in prokaryotes and 80s in eukaryotes)
• both cells contain DNA

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14
Q

Outline two similarities between the structure of prokaryote cells and eukaryote cells.

A

• plasma membrane
• ribosomes (although they are 70s in prokaryotes and 80s in eukaryotes)
• both cells contain DNA

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15
Q

Outline the role of cyclins in living cells

A

• Cyclins control different stages of the cell cycle;
• Concentrations of each cyclin rise and fall in each stage;
• The rise and fall of the concentrations activates proteins;
• The activated proteins carry out reactions specific to the stage of the cell cycle / allow the cell cycle to continue;

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16
Q

Describe one type of cell which is atypical to the concept of cell theory.

A

• Striated muscle – many nuclei along the length of a single cell/muscle fibre
• Giant algae – Large organisms containing only one nucleus
• Hyphal aseptate fungi – hyphae are not divided into cells and contain many nuclei in a single hypha
• Or equivalent example

17
Q

The Davson-Danielli model of the membrane structure proposed a
layer of protein on the outside edges of membranes. Biological
evidence caused them to refine their model and later the SingerNicholson model became accepted as a better model of
membrane structure.
Describe one piece of evidence that falsified the Davson-Danielli
model in support of the Singer-Nicholson model (3 marks)

A

(Hubbell and McConnell 1968 improved methods of) freeze-etching to reveal details of the structure of membranes.
Freeze etching experiments strongly suggest that protein is found deeply embedded in the membrane;
A frozen membrane is fractured and splits along the interior hydrophobic part of the membrane;
A smooth matrix/layer is seen interrupted by particles/proteins is seen;
Allow marks for the following explanations - even if freeze etching is not mentioned;
There was evidence that proteins were present in the middle of the bilayer;
This proved that the Danielli Daveson model couldn’t be correct as this model has no protein in the middle of the lipid bilayer;

18
Q

Define the term “cell differentiation”

A

Cell differentiation is the process by which a cell changes from one cell type (an undifferentiated cell / a stem cell) to another cell type / specialised cell (by expressing some of its genes and not others)

19
Q

Explain the evidence which supports the endosymbiotic theory of the evolution of the
eukaryotic cell

A

• Mitochondria and chloroplasts are believed to have been free living (they are endosymbionts);
• Mitochondira and Chrloroplasts have double membrane which is evidence for endocytosis of the organelle;
• they have 70s ribosomes which are found in Prokaryotes;
• they have a DNA loop/naked DNA as found in Prokaryotes;
• they are self replicating which is evidence for them having been free living origin;

20
Q
  1. Eukaryotic cells contain organelles which each have specific functions. Complete the table below, to identify the missing organelle names and the missing functions.
A

Organelle Structure Function
Nucleus Large structure surrounded by a double membrane with DNA and proteins inside. Contains the cell’s DNAand is the site of DNA replication
Golgi apparatus A stack of four or more flattened membrane disks Processes and packages proteins into vesicles
Lysosome A round organelle with a single membrane containing digestive enzymes. Digestion of molecular debris inside the cell.
Mitochondrion An organelle with a double membrane. The outer membrane makes the shape of the organelle but the inner membrane folds into cristae Carries out the reactions of the Krebs cycle / aerobic respiration

21
Q

Which statement provides evidence for endosymbiosis?

A

Eukaryotic mitochondria and chloroplasts have their own circular DNA.

22
Q

Which of the following are features of prokaryotes and eukaryotes?

A

-70s ribosomes: prokaryotes
-80s ribosomes: eukaryotes
-Naked DNA: prokaryote
DNA associated with proteins: eukaryote

23
Q

What route is used to export proteins from the cell?

A

Rough endoplasmic reticulum - Golgi apparatus - Plasma membrane

24
Q

Which organisms has DNA located in three organelles?

A

A fern

25
Q

Which of the following will contribute to the cell theory?

A
  • Living organisms are composed of cells.
  • All cells come from pre-existing cells by mitosis.
  • Cells are the smallest units of life.
26
Q

Which process is possible due to the fluidity of cell membranes?

A

Endocytosis

27
Q

Which organelle is involved in generating vesicles destined for the cell membrane?

A

Golgi apparatus

28
Q

Which organelle is involved in generating vesicles destined for the cell membrane?

A

Lysosome

29
Q

Which sequence shows increasing relative size?

A

Membrane thickness - Virus - Bacterium

30
Q

In which parts of the digestive system are most water and glucose absorbed?

A

Water: Large intestine
Glucose: Small intestine

31
Q

Which organelle provides evidence that eukaryotic cells originated when prokaryotes engulfed small free-living prokaryotes?

A

Chloroplasts

32
Q

What is the principal mode of division for the prokaryote Escherichia coli?

A

Binary Fission

33
Q

What stage does chromosome supercoiling occur?

A

Prophase

34
Q

What stage does the sister chromatids migrate to opposite poles?

A

Anaphase

Biology (7 decks)

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