CB1- Key Concepts In Bilology

Question 1

Eukaryotes

Answer 1

Cells which have Nuclei such as plant and animal cells

Question 2

Prokaryotes

Answer 2

Cells that don’t have a nuclei such as bacteria.

Instead they have free DNA floating around in the cell.

Question 3

Nucleus function?

Answer 3

Contains DNA and controls activities of the cell.

This genetic material is arranged into chromosomes.

Question 4

Cell membrane function?

Answer 4

Controls what goes in and out of the cell.

Holds the cell together.

Question 5

Mitochondria

Answer 5

Where aerobic respiration occurs and releases energy.

Question 6

Ribosomes function?

Answer 6

Where proteins are made in protein synthesis

Question 7

Cytoplasm

Answer 7

Where chemical reactions take place

It contains enzymes that control these chemical reactions

Question 8

Chloroplasts

Answer 8

Contains chlorophyll (a green substance) to absorbe sunlight. 
Where photosynthesis occurs which makes food for the plant.

Question 9

Vacuole

Answer 9

Contains sap and water which keeps the cell rigid (Maintains internal pressure) to support the cell.

Question 10

Cell wall

Answer 10

Made of cellulose for strength and support to stop the cell from bursting. On outside of plant cell.

Question 11

Plant cells have…

Answer 11

Nucleus 
Cytoplasm 
Cell membrane 
Mitochondria 
Ribosomes 
And
Cell wall
Large vacuole 
Chloroplasts

Question 12

Animal cells have…

Answer 12

Nucleus 
Cytoplasm 
Cell membrane 
Mitochondria 
Ribosomes

Question 13

Microscopes Different parts:

Answer 13

Eyepiece lense
Objective lense 
Stage 
Focusing wheel 
Fine focus 
Base 
Mirror or light

Question 14

What are the differences between old microscopes and a modern one?

Answer 14

Hookes microscope has a resolution of 0.002 mm only one objective lense and a lower resolution and magnification than a light microscope resolution of 0.0001 mm.
An electron microscope is better than both of these with the highest resolution and magnification this allows it to see multicellular structures such as mitochondria.

Question 15

Magnification is…

Answer 15

How many times bigger the image is compared to real life

Question 16

Resolution is…

Answer 16

Smallest distance between two points that can be seen as two separate points.

Question 17

What should a cell always be measured in and why?

Answer 17

In mm

Question 18

Magnification calculation:

Answer 18

Actual size = image size

Magnification

Question 19

Osmosis definition

Answer 19

Is the movement of water molecules across a partially permeable membrane. From an area of high concentration to low concentration (down the concentration gradient)
Only tiny molecules like water can pass through and sucrose cannot

Question 20

Active transport definition

Answer 20

The movement of (mineral) particles across a membrane from an area of low concentration to an area of high concentration (against the concentration gradient)
Unlike the others this requires energy from respiration

Question 21

Concentration

Answer 21

Amount

Question 22

Diffusion (passive process)

Answer 22

Is the movement of (gas) particles from an area of high concentration to an area of low concentration
Only small molecules such as glucose, amino acids, water and oxygen
Starch and protein can’t fit through the membrane.

Question 23

Active transport examples:

Answer 23

1) when there is a higher concentration of nutrients in the gut than In the blood, the nutrients diffuse naturally into the blood.
2) But - sometimes there is sometimes a lower concentration of nutrients in the gut than in the blood.
3) AT - allows nutrients to be taken into the blood despite the fact the concentration gradient is the wrong way. This is essential to stop us from starving.

Question 24

Turgid cell

Answer 24

Water enters by osmosis - vacuole swells and pushes against the cell wall.

Question 25

Flaccid cell

Answer 25

Water is lost from the cell and becomes.

Question 26

Bacterial cells have...

Answer 26

Sub-cellular structures: - chromosomal DNA controls the cells activities and replication And floats free In the cytoplasm - ribosomes - cell membrane - plasmid DNA - small loops of extra DNA that aren’t part of the chromosome. - flagellum rotates to make bacterium move away from toxins and towards beneficial things like nutrients or oxygen.

Question 27

Egg cell

Answer 27

Specialised for its function : Carries female DNA and nurse is the developing embryo in the early stages. 1) contains nutrients in the cytoplasm to feed the embryo 2) has a haploid nucleus 3) straight after fertilisation, membrane changes structure to stop,any More sperm getting in. This makes sure the offspring end up with the right amount of DNA.

Question 28

Sperm cell

Answer 28

Function of a sperm cell is: To transport the males DNA to the females egg. 1) A sperm cell has a long tail so it can swim to the egg 2) it has lots of mitochondria in the middle section the provide energy (from respiration) needed to swim this distance. 3) Acrosome - at the front of the head where it stores enzymes to digest It’s way through the membrane of the egg cell. 4) contains a haploid nucleus.

Question 29

Ciliated epithelial cells

Answer 29

Specialised for moving materials 1) line the surface of organs 2) some have cilia (hair like structures) on the top surface of the cell. 3) the function of these (CEC) is to move substances - the cilia best to move substances in one direction, along the surface of the tissue. 4) for example -lining the airways contain lots of (CEC) these help to move mucus up to the throat so it can be swallowed and doesn’t reach the lungs.

Question 30

Sexual reproduction

Answer 30

In sexual reproduction the nucleus of the egg cell fuses with the nucleus of the sperm cell to create a fertilised egg, which develops into an embryo. Both have haploid nucleus’s meaning when they fuse create a diploid cell that has the correct number of chromosomes.

Question 31

Magnification calculation:

Answer 31

Magnification = image size | Real size

Question 32

Total magnification =

Answer 32

Eyepiece lens magnification x objective lens magnification

Question 33

Converting units - standard form Down- times Back- divide

Answer 33

``` Unit Symbol Equivalent in 
 metres (m) Equivalent in 
 metres (m) centimetre cm 0.01 10- 2 millimetre mm 0.001 10- 3 micrometre µm 0.000 001 10- 6 nanometre nm 0.000 000 001 10- 9 picometre pm 0.000 000 000 001 10- 12 ```

Question 34

Enzymes

Answer 34

enzymes are proteins which act as a biological catalysts which speeds up a reactions whilst still remaining chemically unchanged.

Question 35

For an enzyme to work...

Answer 35

The substrate has to fit into the active site. If the substrates shape doesn’t match the active sites shape then the reaction won’t be catalysed. This is called the lock and key mechanism because the substrate fits into the enzyme just like a key fits into a lock.

Question 36

Lock and key hypothesis

Answer 36

Specific enzyme for a specific substrate

Question 37

Enzymes Catalyse reactions.

Answer 37

The substrate binds to the active site which is complementary in shape. This creates an enzyme substrate complex and the enzyme a product whilst remaining chemically unchanged.

Question 38

Enzyme action: | Temperature

Answer 38

Changing the temperature changes the rate of the enzyme catalysed reaction like with any reaction a higher temperature increases the rate at first but if it gets too hot some of the bonds holding the enzyme together break. This changes the shape of the enzymes active site so the substrate won’t fit anymore The enzyme is said to be denatured. All enzymes have an optimum temperature that they work best at.

Question 39

Enzyme action: | PH

Answer 39

The pH also affects enzymes. If it’s too high or too low the pH interferes with the bonds holding the enzyme together. This changes the shape of the active site and denatures the enzyme. All enzymes have an optimum pH that they work best that it’s often a neutral pH seven but not always e.g. pepsin is an enzyme used to break down proteins in the stomach it works best at PH to which means it’s well suited to the acidic conditions there.

Question 40

Enzyme action: | Substrate concentration

Answer 40

Substrate concentration also affects the rate of reaction – the higher the substrate concentration the faster the reaction. This is because it’s more likely that the enzyme will meet up and react with the substrate molecule. This is only true up to a point though after that there are many substrate molecules that enzymes have about as much as they can cope with all the active site and adding more makes no difference.

Question 41

How to calculate the rate of a reaction.

Answer 41

Rate = 1000 | Time

Question 42

Enzymes break down big molecules:

Answer 42

Proteins, lipids and carbohydrates are big molecules. Important organisms can break these down into their smaller components so they can be used for growth and life processes.

Question 43

Enzymes breaking down food

Answer 43

Many of the molecules in the food we eat are too big to pass through the walls of the digestive system so the digestive enzymes break them down into smaller soluble molecules. These can pass easily through the walls of the digestive system allowing them to be absorbed into the bloodstream. They can then pass on to cells to be used by the body

Question 44

Enzymes in plants

Answer 44

Plant store energy in the form starch (a carbohydrate) when plants need energy enzymes break down starch into smaller molecules sugars. These can be respired to transfer energy to be used by the cells.

Question 45

Different types of enzymes break down (carbohydrates) proteins and lipids

Answer 45

Enzymes called carbohydrases convert carbohydrates into simple sugars e.g. amylase didn’t examples of carbohydrates it breaks down starch into maltose and of the sugars.

Question 46

Enzymes such as protease...

Answer 46

Proteases convert proteins into amino acid‘s

Question 47

Lipases break down

Answer 47

Lipases convert lipids into glycerol and fatty acid