CB1 - Key concepts in Biology

Question 1

What is the function of the Nucleus?

Answer 1

Contains genetic material (DNA). It is arranged into chromosomes.

Question 2

What is the function of the Cell membrane?

Answer 2

Holds the cell together and control what goes in and out.

Question 3

What is the function of the Mitochondria?

Answer 3

Where the most of the reactions for respiration take place. Respiration transfers energy for the cell.

Question 4

What is the function of the Ribosomes?

Answer 4

Involved in translation of genetic material in protein synthesis.

Question 5

What is the function of the Cell wall?

Answer 5

Made of cellulose. Supports the cell and strengthens it.

Question 6

What is the function of the Chloroplast?

Answer 6

This is where photosynthesis occurs. It contains a green substance called chlorophyll.

Question 7

What is the function of the Vacuole?

Answer 7

Contains cell sap (A weak solution of sugars and salts). Maintains internal pressure to support cell.

Question 8

What is the function of the Chromosomal DNA?

Answer 8

Controls cells activities and replication. It floats free in the cytoplasm.

Question 9

What is the function of the Plasmid DNA?

Answer 9

Small loops of extra DNA that aren’t part of the chromosomes. Contains genes for things like drug resistance.

Question 10

What is the function of the flagella?

Answer 10

A long hair-like structure that rotates to make bacterium move.

Question 11

What is the function of the Acrosome?

Answer 11

At the front of the sperm. Stores enzymes needed to digest through membrane of egg.

Question 12

What is the function of the Haploid nucleus?

Answer 12

Contains genetic info for fertilisation.

Question 13

What is the function of the Tail?

Answer 13

Helps sperm to swim in egg cell.

Question 14

What is the function in the nutrients in the cytoplasm?

Answer 14

Feeds the embryo.

Question 15

What changes in the cell membrane after fertilisation?

Answer 15

Changes structure so does not let any sperm in. Makes sure that offspring have right amount of DNA.

Question 16

What is Ciliated epithelial cells?

Answer 16

Line the surface of organs. Function : Moves substance - the cilia move substance in one direction.

Question 17

What is the difference between Light and Electron microscopes?

Answer 17

Light : Invented in 1950’s. Work by passing light through specimen. Let us see nuclei and chloroplast.
Electron : Invented in 1930’s. Use electron than light. Have higher magnification and resolution, so let us see smaller things like internal structure. Allowed us to have much greater understanding of how cells works.

Question 18

When should Estimation should be used?

Answer 18

When there is no scale.

Question 19

Millimetre (mm)

Answer 19

Standard form : 10-3
Millimetre to Micrometre : x1000

Question 20

Micrometre (µm)

Answer 20

Standard from : 10-6
Micrometre to Nanometre : x1000

Question 21

Nanometre (nm)

Answer 21

Standard form : 10-9
Nanometre to Picometre : x1000

Question 22

Picometre (pm)

Answer 22

Standard form : 10-12

Question 23

Practical : Investigate biological specimen under a microscope

Answer 23

1. Make thin slice of specimen
2. Take a clean slide and put one drop of water on (Secure specimen on slide)
3. Use tweezers to put specimen on slide
4. Add drop of stain if specimen it transparent.
5. Put cover slip carefully on specimen and make sure there is no air bubbles.
6. Clip the slide onto stage.
7. Select lowest- powered objective lens
8. Adjust the focus with fine adjustment knob until you get a clear image.

Question 24

How to calculate Total Magnification?

Answer 24

Total Magnification = Eyepiece lens mag x Objective lens mag

Question 25

How to calculate Magnification?

Answer 25

Magnification = Image size / Real Size

Question 26

How to draw Scientific drawing of specimen?

Answer 26

1. Use a sharp pencil and draw outlines of main feature using clear, unbroken lines. 2. Make sure drawing takes half of the space given to draw. 3. Label the important features of your diagram and don't cross over and include magnification and use a scale.

Question 27

Explain the mechanism of enzyme action?

Answer 27

For enzyme to work, substrate has to fit into active site. If it does not fit, the reaction wont be catalysed. It is called "Lock and Key mechanism".

Question 28

What is the Active site?

Answer 28

Every enzyme has active site - Part where it joins on to substrate to catalyse.

Question 29

What is Enzyme Specificity?

Answer 29

Limitation of enzyme to catalyse one specific reaction with one specific substrate.

Question 30

Explain how enzymes can be denatured due to changes in shape of active site?

Answer 30

If enzyme exposed to high temp, the shape of active site may change.

Question 31

Explain the effect of temperature on enzyme activity?

Answer 31

Changing temp changes rate of enzyme reaction. A high temp increases rate till certain point, if increases from this point the binds will break holding the enzyme together. The enzyme is **denatured**. All have an optimum temp where they work the best.

Question 32

Explain the effect of substrate concentration on enzyme activity?

Answer 32

Affects rate of reaction - higher the substrate conc, faster the reaction. More likely that enzyme will meet up and react with substrate molecule.

Question 33

Explain the effect of pH on enzyme activity?

Answer 33

pH also effects enzyme. If it's too high or low, pH interferes and holds the binds. Changes shape of active site and denature. All enzyme have optimum pH, mostly pH 7.

Question 34

Practical : Investigate effect of pH on enzyme activity

Answer 34

1. Put a drop of iodine in every spotting tile 2. Set a Bunsen burner. Put a beaker on to the tripod and heat water until 35 Celsius (try to keep temp constant). 3. Use syringe to add 3cm^3 of amylase solution and 1cm^3 of buffer solution with pH 5 to boiling tube - put tube in beaker. 4. Use different syringe to add 3cm^3 of starch solution to tube. 5. Mix contents and start a stop clock. 6. Use continuous sampling to record how long it takes for starch to break. 7. Use a pipette and take a fresh sample every ten seconds and drop into spotting tile. When iodine solution remains browny orange, starch is not present.

Question 35

How to calculate Rate of Reaction?

Answer 35

Rate = 1000/time Units = s^-1

Question 36

Explain the importance of enzyme as biological catalyst?

Answer 36

Human body needs to digest food to release energy. Small molecules can be used to build larger molecules that are needed in cells and tissue.

Question 37

Practical : Investigate use of chemicals regents to identify Starch.

Answer 37

1. Add starch in iodine solution. If starch present, sample changes colour to dark-black. If not present, stays browny-orange

Question 38

Practical : Investigate use of chemicals regents to identify reducing sugar.

Answer 38

1. Add Benedict's reagent to a sample and heat in water bath.75 2. If test positive. it will form a colour precipitate. Higher the conc of reducing sugar, further the colour changes. Blue->green->yellow->orange->red

Question 39

Practical : Investigate use of chemicals regents to identify lipids (fats).

Answer 39

1. Shake test substance with ethanol until it dissolves. 2. Pour solution into water 3. If any lipids present, a precipitate will show up as milky emulsion.

Question 40

Practical : Investigate use of chemicals regents to identify Proteins.

Answer 40

1. Add a few drops of potassium hydroxide solution to make solution alkaline. 2. Add some copper II sulfate to solution If no protein, solution will be blue. If protein is present, solution will be purple.

Question 41

Explain how the energy in food can be calculate using calorimetry? (Experiment)

Answer 41

1. Get a food that will burn easily 2. Weigh it and skewer it on mounted needle 3. Add a set of volume of water to boiling tube 4. Measure temp of water, then set fire to food using Bunsen Burner 5. Hold burning food under boiling tube until it goes out. Relight food again till food wont catch fire. 6. Measure temp of water again.

Question 42

Explain how the energy in food can be calculate using calorimetry? (Calculations)

Answer 42

Energy = Mass of water x Temp change in water x 4.2 Energy = J Mass of water = g Temp change = Celsius THEN Energy per gram of food = Energy / Mass of food Energy per gram of food = J/g

Question 43

What is Diffusion?

Answer 43

Movement of particles from an area of higher conc to an area of low conc. Happens in liquid and gas Only very small molecules can diffuse. Does not need energy.

Question 44

What is osmosis?

Answer 44

Movement of water particles from an area of high conc to low conc through a partially permeable membrane. Does not need energy.

Question 45

What is active transport?

Answer 45

Movement of particles from an area of low conc to high conc against a conc gradient. Requires energy.

Question 46

Practical : Investigating osmosis in potatoes.

Answer 46

1. Prepare sucrose solution of different ranges 2. Cut out potato into same sized pieces 3. Use a balance to measure mass of potatoes 4. Place potatoes in solution and leave for 40 minutes 5. Remove potatoes and pat dry gently 6. Measure the mass of potatoes again

Question 47

Calculate percentage gain and loss in osmosis.

Answer 47

Percentage change = (Final mass - Initial Mass)/Initial mass x 100.