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Biology > Key Concepts of Biology > Flashcards

Key Concepts of Biology Flashcards

1
Q

What are the key components of eukaryotic (animal and plant) cells?

A

Eukaryotic cells contain a cell membrane, cytoplasm and a nucleus.

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2
Q

What distinguishes prokaryotic (bacterial) cells from eukaryotic cells in terms of structure?

A

Prokaryotic cells have a cell wall, cell membrane, cytoplasm and a singular strand of DNA along with plasmids.

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3
Q

Where do chemical reactions occur within a cell?

A

Cytoplasm

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4
Q

What is the function of the mitochondria within animal and plant cells?

A

Mitochondria are responsible for aerobic respiration, providing energy for the cell.

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5
Q

Where does protein synthesis occur within a cell?

A

Ribosomes

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6
Q

What organelles are unique to plant cells compared to animal cells?

A

Chloroplasts, permanent vacuole and cell wall.

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7
Q

What is the function of chloroplasts?

A

This is where photosynthesis occurs, providing food for the plant.
Contains chlorophyll, which harvests the light needed for photosynthesis.

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8
Q

What is the function of the permanent vacuole?

A

Contains cell sap and contributes to the rigidity of the cell.

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9
Q

What is the function of the cell wall?

A

It provides strength and rigidity to the cell, as it is made from cellulose.

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10
Q

What are the key structures found in bacterial cells?

A

Bacterial cells have a cell wall, chromosomal DNA (circular) and plasmids.

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11
Q

What is the function of plasmids?

A

They are small rings of DNA, which can contains additional genetic information.

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12
Q

What is the function of chromosomal DNA (circular)?

A

As bacteria cells have no nucleus, this floats in the cytoplasm.

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13
Q

What is the function to the flagella?

A

They are long tails attached to the bacteria that enable them to move.

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14
Q

What is cell differentiation?

A

A process where cells acquire new subcellular structures to perform specific functions.

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15
Q

How are sperm cells specialized for their function?

A

They have a streamlined head and a long tail to aids swimming, along with mitochondria to supply energy.
They also contains an acrosome with digestive enzymes to break down the outer layers of the cell during fertilization.

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16
Q

How are egg cells specialized for their function?

A

They are surrounded by a special membrane that allows only one sperm to fertilize them, becoming impermeable after fertilization.
Also contain lots of mitochondria to provide energy for the developing embryo.

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17
Q

What is the function of ciliated epithelial cells?

A

They are specialized to waft bacteria trapped by mucus down to the stomach, where they are killed by stomach acid.

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18
Q

How are electron microscopes advantageous over light microscopes?

A
  1. Appear bigger/more magnified
  2. Can see the cells in more detail/higher resolution
  3. can see more organelles e.g mitochondria/ribosome
  4. Image would be black and white
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19
Q

What is the formula of calculating total magnification?

A

Total magnification = magnification of the objective lens x magnification of the eyepiece lens

20
Q

How is magnification calculated?

A

Magnification = Measured size/Actual size

21
Q

What are the common units used?

A

m (milli) 10-3
µ (micro) 10-6
n (nano) 10-9
p (pico) 10-12

22
Q

What is the function of the eyepiece in a light microscope?

A

Used to look and view specimens.

23
Q

What is the purpose of the barrel in a light microscope?

A

The barrel is the upper part of the microscope that can be moved up or down to focus the image.

24
Q

What is the function of the turret in a light microscope?

A

The turret is rotated to change the magnification lens in use.

25
Q

What is the purpose of the lens in a light microscope?

A

To increase the magnification of the specimen.

26
Q

What is the stage in a light microscope used for?

A

The stage is a flat surface where specimens are placed for observation.

27
Q

CORE PRACTICAL - Investigating a light microscope (4)

A
  1. Place the slide on the stage and look through the eyepiece lens.
  2. Turn the focus wheel to obtain a clear image.
  3. Start with the lowest objective lens magnification.
  4. Increase the magnification of the objective lens and refocus as needed.
28
Q

What are enzymes?

A

Enzymes are biological catalysts that increase the rate of a reaction without being used up themselves.
They function by forming enzyme-substrate complexes, where the shape of the substrate is complementary to the shape of its active site.

29
Q

How does temperature affect enzyme activity?

A

The rate of enzyme activity increases with temperature up to an optimum, beyond this the enzyme denatures due to the breaking of bonds holding its structure together, leading to decrease in activity.

30
Q

How does pH affect enzyme activity?

A

pH influences enzyme activity by altering the shape of the active site, reducing the enzyme activityas less enzyme-substrate complexes are being formed.

31
Q

What is the significance of substrate concentration on enzyme activity?

A

Increasing substrate concentration initially increases the rate of enzyme activity until reaching saturation where all enzyme active sites are occupied, and then do not affect the rate of reaction

32
Q

CORE PRACTICAL - Investigating the effect of pH on enzyme activity (6)

A
  1. Place drops of iodine solution on each tray.
  2. Label a test tube with the pH to be tested. Place it in a beaker with cold water and place this above the Bunsen burner for 3 minutes.
  3. Place amylase solution, starch solution and the buffer pH solution in a test tube and start a stopwatch.
  4. After 10 seconds, use a pipette to place a drop of the solution into one of the wells containing iodine solution. The mixture should turn blue-black to indicate that starch is still present and has not yet been broken down.
  5. Repeat step 4 after another 10 seconds. Continue repeating until the solution remains orange and record the time taken.
  6. Record your results on a graph of pH and time taken.
33
Q

Why do we use and Bunsen burner and water during the investigation of the effect of pH on enzyme activity?

What results do we expect from this experiment?

A

To maintain a relatively constant temperature throughout the reaction.

That the optimal pH for amylase will be the pH at which the reaction completes in the shortest time.

34
Q

How do we calculate the rate of enzyme activity?

A

Rate = Change/Time

35
Q

What are some examples of enzymes acting as biological catalysts? (3)

A

Carbohydrases convert carbohydrates into simple sugars.
Proteases convert proteins into amino acids.
Lipases convert lipids into fatty acids and glycerol.

36
Q

What reagent/test is used to detect the presence of starch and devise a method?

A

Iodine solution
Add iodine solution to the food sample. If starch is present the colour will change from orange to blue-black.

37
Q

What reagent/test is used to detect the presence of reducing sugars and devise a method?

A

Benedict’s solution
Add the sample solution and the blue Benedict’s solution to a test tube. Place in a boiling water bath for a few minutes or until there is no further change. Presence of reducing sugars is indicated by a colour change to reddish-brown.

38
Q

What reagent/test is used to detect the presence of protein and devise a method?

A

Biuret test ( potassium hydroxide and copper sulfate)
Add potassium hydroxide to the food sample and then add the same amount of copper sufate. Shake well and observe if protein is present it will turn from blue to violet.

39
Q

What reagent/test is used to detect the presence of lipids (fat and oils) and devise a method?

A

Emulsion Test
Add ethanol to food sample and shake. Add deionised water and shake. If lipids are present this will be indicated by the formation of white emulsion layer at the top of the sample.

40
Q

What is calorimetry?

A

A way to measure the energy taken in and given out during a chemical reaction.

41
Q

How to measure calorimetry? (4)

A

1.Take a tube of cold water.
2.Record the starting temperature of the water.
Place the test tube at 45 degrees and hold a burning food sample just beneath it.
4. When the food is burned up, record the final temperature of the water.

42
Q

Describe the process of diffusion

A

The movement of particles from a high concentration to a lower concentration.

43
Q

Describe the process of osmosis

A

The movement of water molecules through a semi-permeable membrane from a high concentration to a lower concentration.

44
Q

Describe the process of active transport

A

The movement of substances against their concentration gradient from a low concentration to a high concentration across a partially permeable membrane. This requires energy.

45
Q

CORE PRACTICAL - Osmosis in potatoes (6)

A
  1. Cut potato into small discs of equal sizes.
  2. Blot the potato disks gently with tissue paper to remove excess water.
  3. Measure the initial mass of each potato.
  4. Blot the potato in sucrose solutions of different concentrations.
  5. Blot the potatoes again and record the new mass.
  6. Find the difference in mass and use the percentage change equation to calculate percentage gain or loss of mass.
    Percentage change equation = (Change in mass/Start mass) x 100
46
Q

What are the independent, dependent and control variables in the osmosis experiment?

A

Independent - we are changing the concentration of the sucrose solution.
Dependent - we are measuring the change in mass of potato disks.
Control - we are controlling the diameter of the disks.

Biology (9 decks)

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