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Unit 2 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Eukaryotic cells compared with Prokaryotic Cells (7)

A
  1. Bacterial cell is much smaller then a human cell
  2. Bacterial cell has a cell wall but human cells does not
  3. Bacterial cells lacks a nucleus but human cells contain a nucleus
  4. Bacterial Cells lack membrane-bound organelles but human cell has membrane-bound organelles
  5. Bacterial ribosomes (70s) smaller then human ribosomes (80s)
  6. Bacterial DNA is circular but human DNA is linear
  7. Bacterial DNA is not associated to histones whereas Human DNA is bound to histones
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2
Q

Describe the structure and function of the nucleus (4)

A

Structure: Nuclear envelope
Nuclear Pores in membrane
Chromosomes with histones
Nucleolus
Function: Holds genetic information for
production of proteins
DNA replication
Production of mRNA
Production of rRNA

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3
Q

Name the polymer that forms the following cell walls in plants and fungi?

A

Cellulose in plants
Chitin in fungi

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4
Q

Describe the role of one eukaryotic organelle in digesting bacteria (3)

A
  1. Lysosomes
  2. Fuse with the vesicles
  3. Release hydrolytic enzymes
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5
Q

Identify two organelles in cells that enable the production of glycoproteins

A

Rough Endoplasmic Reticulum and Golgi Vesicle

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6
Q

Give two structures found in all prokaryotic cells and in all eukaryotic cells (2)

A
  1. Cell Membrane
  2. Ribosomes
  3. Cytoplasm
  4. DNA
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7
Q

Give 1 feature of the chloroplast that allows protein to be synthesised inside the chloroplast and describe one difference between this feature in the chloroplast and a eukaryotic cell (2)

A
  1. DNA
  2. Is not associated with histones, but nuclear DNA is
  3. Ribosomes
  4. Are smaller than cytoplasmic ribosomes
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8
Q

Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells (4)

A
  1. DNA in nucleus codes for proteins
  2. Ribosomes/Rough Endoplasmic Reticulum produce protein
  3. Mitochondria produce ATP for protein synthesis
  4. Golgi apparatus package/modify the protein
  5. Vesicles transport the protein
  6. Vesicles fuse with the cell membrane
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9
Q

State three differences between DNA in the nucleus of plant cell and the DNA in a prokaryotic cell (3)

A
  1. Associated with histones vs Not associated with histones
  2. Linear vs Circular
  3. No plasmids v Plasmids
  4. Introns vs No introns
  5. Longer vs Shorter
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10
Q

Name the main biological molecule in the cell membrane (1)

A

Phospholipids

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11
Q

Describe the role of mitochondria in secreting a protein (1)

A

Many Mitochondria release energy for protein synthesis

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12
Q

Describe the role of Golgi apparatus in secreting a protein (1)

A

Mang Golgi vesicles transport protein out of the cell

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13
Q

Describe the role of the Golgi apparatus in lipid absorption

A
  1. Modifies triglycerides
  2. Combines triglycerides with proteins
  3. Packaged for release
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14
Q

Name the biological molecule in a bacterial cell wall (1)

A

Murein

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15
Q

Give two features of all prokaryotic cells that are not features of eukaryotic cells

A
  1. Cytoplasm with no membrane-bound organelles
  2. Single, Circular DNA
  3. DNA free in the cytoplasm
  4. DNA that is not associated with histones
  5. A cell wall that contains murein
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16
Q

Give 2 features of all viruses (2)

A
  1. Attachments proteins
  2. Capsid
  3. Nucleic Acid
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17
Q

How to measure objects using an eyepiece graticule (3)

A
  1. Use eyepiece graticule to measure the object
    2.Calibrate eyepiece graticule against stage micrometre
  2. Take a number of measurements and calculate the mean
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18
Q

Advantages and Limitations of TEM (6)

A

Advantages:
1. Small objects can be seen
2. TEM has a high resolution as wavelength of electrons are shorter.

Limitations:
1. Cannot look at living cells as cells must be in a vacuum
2. Must be thin specimen, 1 cell thick
3. Preparation may create artefact
4. Does not produce colour image

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19
Q

Comparison of TEM and optical microscope (8)

A
  1. TEM use electrons and optical use lights
  2. TEM allows a greater resolution
  3. With TEM, smaller organelles can be observed
  4. TEM can view only dead specimens
  5. TEM does not show colour
  6. TEM requires thinner specimens
  7. TEM requires a more complex slide preparation
  8. TEM focuses using magnets and glass lenses
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20
Q

Advantage of electron microscope over optical microscope (2)

A
  1. High Resolution
  2. Can see internal structure of organelles
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21
Q

The resolution of an image from a electron microscope is higher than the resolution of an image from an optical microscope. Explain Why (2)

A
  1. Shorter wavelength between electrons
  2. So higher resolution
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22
Q

Describe and explain one difference between TEM and SEM (2)

A
  1. 3D image with SEM, not 2D image
  2. Because electrons bounce off SEM
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23
Q

Conditions required for cell homogenisation (3)

A
  1. Ice-cold: Stops enzyme activity to prevent damage to the organelles
  2. Buffered - Maintains pH so enzymes don’t become denatured
  3. Isotonic - Prevents osmosis so no bursting of organelles
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24
Q

How to separate mitochondria from cell sample? (4)

A
  1. Break open cells
  2. Remove cellular debris by filtration
  3. Add isotonic, buffered and cold solution.
  4. Centrifuge at the highest density, so a pellet of the nuclei forms
  5. Remove pellet, then spin at higher, faster speeds. So pellet of mitochondria forms at the bottom
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25
Q

Suggest why scientists can use detergent to break open cells instead of homogenisation (2)

A
  1. Cell membranes made from phospholipid
  2. Detergent dissolves membranes
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26
Q

Describe Viral Replication (4)

A
  1. Attachment proteins attach to receptors
  2. Virus injects nucleic acid
  3. Reverse Transcriptase converts RNA into DNA
  4. Viral Protein is Produced
  5. Virus released
27
Q

Describe binary fission in bacteria (3)

A
  1. Replication of circular DNA
  2. Replication of plasmids
  3. Division of cytoplasm
28
Q

Describe how bacteria divide (2)

A
  1. Binary fission
  2. Replication of circular DNA
  3. Division of cytoplasm to produce 2 daughter cells
  4. Each with single copy of circular DNA
28
Q

What is a tumour?

A
  1. Mass of cells
  2. Many cells in mitosis
29
Q

Describe and explain the arrangement of the genetic material in prophase (2)

A
  1. Chromosomes become visible
  2. Because it’s still condensing
  3. Chromosomes are arranged at random
  4. Because there’s no spindle activity
30
Q

Chromosome Behaviour in all Stages (8)

A

During Prophase:
1. Chromosomes coil and become visible
2. Chromosomes appear as Chromatids are joined at the centromere
During Metaphase:
3. Chromosomes line up on the equator
4. Chromosomes attached to the spindle fibre
5. By their centromere
During Anaphase:
6. Centromere splits
7. Sister Chromatids are pulled to opposite ends of the cell
During Telophase:
8. Chromatids uncoil

31
Q

Describe the role of the spindle fibres and the behaviour of the chromosomes during mitosis (5)

A
  1. In Prophase chromosomes condense
  2. In Prophase centromeres attach to spindle fibres
  3. In metaphase chromosomes are lined to equator of the cell.
  4. In anaphase centromeres divide
  5. In anaphase chromatids are pulled to opposite ends of the cell
  6. In prophase the spindle fibres shorten
32
Q

State the name given to the division of cytoplasm during the cell cycle (1)

A

Cytokinesis

33
Q

Give two pieces of evidence that the cell was undergoing mitosis (2)

A
  1. The individual chromosomes are visible because they have condensed
  2. Each chromosome is made up of two chromatids because DNA has been replicated
  3. The chromosomes are not arranged in homologous pairs, which they would be if it was meiosis.
34
Q

Evidence for a cell in anaphase (2)

A
  1. Chromosomes are in two groups on opposite ends of spindle
  2. V-shape shows that chromatids have been pulled apart at their centromeres
35
Q

During the cell cycle, the amount of DNA in a cell changes. Explain how the behaviour of chromosomes causes these changes in the amount of DNA per cell (2)

A
  1. Chromosomes replicate
  2. Homologous chromosomes separate
  3. Sister Chromatids separate
36
Q

Suggest why preventing the formation of spindle fibres stopped the cell cycle

A
  1. Chromosomes cannot attach to spindle
  2. So no metaphase
  3. So, Chromatids cannot separate
  4. So, no anaphase
37
Q

Describe the appearance of chromosomes in anaphase (1)

A

Chromatids are being pulled to opposite ends of the spindle

38
Q

Suggest and explain how two environmental variables could be charged to increase the growth rate of cells. (4)

A
  1. Increased concentration of glucose, so increased respiration
  2. Increased concentration of oxygen, so increased respiration
  3. Increased temperature, so increased enzyme activity
  4. Increased concentration of phosphate, so increased ATP
  5. Increased concentration of nucleotides, so increased DNA
39
Q

Req Prac 2, Suggest why the student soaked the root tips in hydrochloric acid

A
  1. To break down links between cell wall
  2. Allowing the stain to diffuse into the cells
40
Q

Req Prac 2, Pressing the coverslip downwards enabled the student to observe the stages of mitosis clearly. Explain why?

A
  1. To break down links between cell walls
  2. Allowing the stain to diffuse into the cells
41
Q

Req Prac 2, Why do we only use the first 5 mm from the tip of the onion root (1)

A

Where mitosis occurs.

42
Q

Req Prac 2, Describe how you would determine a reliable mitotic index (MI) from tissue observed with an optical microscope.

A
  1. Count cells in mitosis in field of view
  2. Divide this by total number of cells in field of view
  3. Repeat 10 times and then calculate a mean
43
Q

Req Prac 2, 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.

A
  1. Examine large number of fields of view
  2. To ensure it’s reliable
  3. Repeat count
  4. To ensure figures are correct
  5. Method to deal with part cells shown at edge
  6. To standardise counting
44
Q

Req Prac, 2 Suggest why different student may get a different mitotic index using the same methos, assume no errors (2)

A
  1. Garlic grown for different lengths
  2. The root tips from different species
  3. Single field of view is not representative of a root tip
45
Q

The Scientist measured the percentage change in tumour volume.
Suggest why they recorded both percentage change and tumour volume (2)

A
  1. To allow comparison as tumours may differ in volume
  2. As tumours may differ in length/shape
46
Q

Describe how proteins arrange themselves in the membrane (2)

A
  1. Hydrophobic parts of helix sit within the fatty acid of the phospholipid
  2. Hydrophilic parts of helix as ions are charged
47
Q

Describe the role of cholesterol (1)

A

Cholesterol stabilises the membrane

48
Q

Name and describe 5 ways substances can move across the cell surface membrane into a cell (5)

A
  1. Simple Diffusion - Net Movement of non-polar down a concentration gradient
  2. Facilitated Diffusion - Movement of substances down a concentration gradient via protein carrier/channel
  3. Osmosis - Net movement of water down a water potential gradient
  4. Active Transport - Movement of substance against a concentration via protein carrier using ATP
  5. Co-transport - Transport of 2 substances using a carrier protein
49
Q

The movement of substances across cell membrane is affected by membrane structure. Describe how? (5)

A
  1. Phospholipid bilayer allows movement of non-polar substances
  2. Phospholipid prevents movement of polar substances
  3. Carrier protein allows active transport
  4. Channel/Carrier proteins allow facilitated diffusion
  5. Shape of Channel/Carrier determines which substances move
  6. Number of channels/carriers determines how much movement
50
Q

Give two similarities in the movement of substances by diffusion and by osmosis (2)

A
  1. Movement down a gradient from high to low concentration
  2. Passive not active process
51
Q

What two factors affect the rate of facilitated diffusion (2)

A
  1. Concentration
  2. Number of channel/carrier proteins
52
Q

Suggest and explain two ways the cell-surface membranes may be adapted to allow rapid transport of nutrients (2)

A
  1. Membrane folded so increased surface area
  2. Large number of protein channels/carriers for facilitated diffusion
  3. Large number of protein carries for active transport
  4. Large number of protein for co-transport
53
Q

Describe how substances move across cell-surface membranes by facilitated diffusion (3)

A

1.. Carrier/channel proteins
2. Protein complementary to substance
3. Substance moves down concentration gradient

54
Q

Contrast the processes of facilitated diffusion and active transport (3)

A
  1. Facilitated diffusion involves channel or carrier proteins where active transport only involves carrier proteins
  2. Facilitated diffusion does not use ATP while active transport does
  3. Facilitated diffusion takes place down a concentration gradient whereas active transport can occur against a concentration gradient
55
Q

Why does inhibiting respiration prevent active transport? (4)

A
  1. Oxygen is required for aerobic respiration which releases ATP
  2. ATP is needed to change the shape of the protein carrier
  3. Which would cause the release of the transported molecule
  4. So no ATP
56
Q

Req Prac 3, How do we find water potential of plant tissue practically? (3)

A
  1. Plot a graph with concentration on the x-axis and percentage change in mass on the y-axis
  2. Find concentration where curve crosses the x-axis
  3. Use resource to find water potential of sucrose concentration
57
Q

Req Prac 4, Describe an experiment that you could do to investigate whether the mangrove root cells have a lower water potential than sea water.
You are given:
*   a piece of fresh mangrove root

*   sea water

*   access to laboratory equipment.

A
  1. Record mass before and after
  2. Place in sea water for specified time
  3. Remove surface water by gently rubbing
  4. Increase in mass will show water has been absorbed by osmosis
  5. Repeat minimum of 3 times
58
Q

Req Prac 4, Give one way in which the student could ensure the first three beetroot cylinders were kept at 25C throughout the experiment (1)

A

Measure temperature at intervals and use appropriate corrective measure

59
Q

Req Prac 4, How does a high temperature disrupt membranes (2)

A
  1. By denaturing the protein
  2. By increasing the permeability of the membrane
60
Q

Req Prac 4, How does alcohol disrupt membranes (1)

A

Ethanol dissolves the phospholipid bilayer

61
Q

Req Prac 4, Use your knowledge of membrane structure to explain how high temperature can cause an increase in absorbance (1)

A

Higher absorbance indicates more pigment released

62
Q

Rec Praq 4, Explain why it is important to control the volume of water in each test tube (1)

A
  1. If too much water the concentration of pigment will be lower
  2. So results are comparable
63
Q

Describe the role of Antibodies in producing a positive result in an ELISA test (4)

A
  1. First antibody binds to antigen
  2. Second antibody with enzyme attached is added
  3. Second antibody attaches to enzyme
  4. Substrate added and colour changes

Biology Flash Cards (8 decks)

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