M2C2 - Basic Components of Living Systems

Question 1

Equation for magnification

Answer 1

Magnification = Image Size / Actual Size

Question 2

Components of a microscope

Answer 2

Eye piece lens, Course focus knob, fine focus knob, turret, object lens, stage, light source

Question 3

Name 3 stains and their function

Answer 3

1) Iodine - stains starch blue/black
2) Methyl blue - stains nuclei blue/purple
3) Eosin - stains cytoplasm pink

Question 4

Magnification

Answer 4

The degree to which the size of an image is larger then the object itself

Question 5

Resolution

Answer 5

The degree to which it is possible to distinguish between two separate points

Question 6

Name the different types of microscopes

Answer 6

Compound light microscope, laser scanning confocal microscope, transmission electron microscope and scanning electron microscope

Question 7

Compound light microscope

Answer 7

Up to 2,000X
Uses visible light to illuminate a thin section of sample
Looks at living things
Looks at cells and tissues
Low resolution compared to other microscopes

Question 8

Laser scanning confocal microscope

Answer 8

Up to 2,000X
Lets you look at thin ‘slices’ in a sample while keeping sample intact.
Looks at living cells
Highlighting individual components of a cell
Fluorescent can cause artefacts.

Question 9

Transmission electron microscope

Answer 9

Up to 5,000,000X
Looks at internal structures
High resolution
Can’t look at living things
Costly to run

Question 10

Scanning electron microscope

Answer 10

Up to 500,000X
Looks at objects in 3D
Resolution greater then light and scanning, but not as high as TEM.
Can’t look at living things.

Question 11

Cell walls

Answer 11

Found in plants but not in animal cells.
Formed outside of the cell membrane and offers structural support to the cell.
Polysaccharide cellulose in plants, and peptidoglycan in bacterial cells.
Narrow threads of cytoplasm called plasmodesmata connect the cytoplasm to neighbouring plant cells

Question 12

Nucleus

Answer 12

Present in all eukaryotic cells and is relatively large.
Separated from the cytoplasm by a double membrane (nuclear envelope)
Contains chromatin which makes up chromosomes.

Question 13

Mitochondria

Answer 13

Site of aerobic respiration within all eukaryotic cells.
Surrounded by a double membrane with the inner membrane folded to form cristae
Matrix formed around the cristae containing enzymes needed for aerobic respiration.
Small circular DNA and ribosomes found in the matrix.

Question 14

Chloroplasts

Answer 14

Found in plants.
Surrounded by a double-membrane.
Contains thylakoids and lamellae.
Small circular pieces of DNA and ribosomes used to synthesis proteins needed in chloroplast replication and photosynthesis.

Question 15

Ribosomes

Answer 15

Found freely in all cells or part of the rough endoplasmic reticulum.
Complex of ribosomal RNA (rRNA) and proteins.
Site of translation.

Question 16

Rough Endoplasmic reticulum

Answer 16

Found in plant and animal cells
Surface covered in ribosomes
Formed from continuous folds of membrane continuous with the nuclear envelope.
Processes proteins made by the ribosomes

Question 17

Smooth Endoplasmic Reticulum

Answer 17

Found in plant and animal cells
Doesn’t have ribosomes on the surface
Involved in the production, processing and storage of lipids, carbohydrates and steroids.

Question 18

Golgi apparatus

Answer 18

Found in plant and animal cells
Flattened sacs of membrane (similar to SER)
Modifies proteins and lipids before packaging them into vesicles.

Question 19

Permanent vacuoles

Answer 19

A sac in plant cells surrounded by the tonoplast.
Vacuoles in animal cells are not permanent

Question 20

Vesicles

Answer 20

Found in plant and animal cells
Membrane-bound sac for transport and storage

Question 21

Lysosome

Answer 21

Specialist forms of vesicles with contain hydrolytic enzymes
Break down waste materials such as worn-out organelles
Used extensively by cells of the immune system

Question 22

Centrioles

Answer 22

Hollow fibres made of microtubules
Two centrioles at right angles to each other from a centrosome, which organises the spindle fibres during cell division
Not found in flowering plants and fungi.

Question 23

Microtubules

Answer 23

Found in all eukaryotic cells
Makes up the cytoskeleton of the cell
Made of alpha and beta tubulin combined to form dimers (which join to form protofilaments)
The cytoskeleton is used to provide support and movement of the cell.

Question 24

Microvilli

Answer 24

Found in specialised animal cells
Cell membrane projections.
Used to increase the surface area of the cell surface membrane.

Question 25

Cilia

Answer 25

Hair like projections made from microtubules
Allows the movement of substances over the cell surface

Question 26

Flagella

Answer 26

Found in specialised cells
Similar structure to cilia but longer microtubules.
Contract to provide cell movement (e.g. sperm cells)

Question 27

Protein synthesis

Answer 27

1) The protein are synthesised on the ribosomes bound to the RER
2) They then pass through into the cisternae and are packaged into transport vesicles
3) Vesicles move towards the Golgi apparatus via the cytoskeleton
4) The vesicles fuse with the cis face of the Golgi apparatus and the proteins enter. The proteins are modified before leaving the Golgi apparatus in vesicles from the trans face
5) Secretory vesicles carry proteins that are to be released from the cell. The vesicles move towards and fuse with the cell-surface membrane, releasing their content by exocytosis.

Question 28

What is the Cytoskeleton

Answer 28

Network of protein threads that run through the cytoplasm.

Question 29

Difference between eukaryotic and prokaryotic cells

Answer 29

Prokaryotes have no membrane-bound organelles.
Prokaryotes have smaller ribosomes (70S) compared to eukaryotic ribosomes (80S)
Eukaryotes like plants and fungi have cells walls made of cellulose and chitin. Bacterial cell walls are made of murein.
Prokaryotic cells are much smaller than eukaryotic cells.
Both prokaryotes and eukaryotes have flagella but those found in prokaryotes are made of flagellin whereas in eukaryotes they’re formed from microtubules.

Question 30

Organelles in prokaryotes that aren’t in eukaryotes

Answer 30

Pili - hair like structures which are used to communicate with other cells.
Plasmids - Small circular rings of DNA which are separate from the main chromosomes
Slime capsule - Protect bacterium against a immune system attack.