2 Basic components of living systems

Question 1

How is a dry mount prepared?

Answer 1

• Solid specimens are viewed whole or cut into very thin slices (sectioning)
• Specimen is placed on the centre of slide and a cover slip is placed over sample

Question 2

How is a wet mount prepared?

Answer 2

• Specimens are suspended in a liquid such as water or an immersion oil.
• A cover slip is placed on from an angle.
• E.g aquatic samples can be viewed this way

Question 3

What is a squash slide?

Answer 3

1) A wet mount is first prepared
2) The sample is squashed between two slides
E.g root tip squashes used to look at cell division

Question 4

What is a smear slide?

Answer 4

1) The edge of a slide is used to smear the sample creating a thin even coating
2) A cover slip is then placed over the sample
E.g sample of blood to view cells in blood

Question 5

What is resolution?

Answer 5

The ability to see individual objects as seperate entities.

Question 6

What is magnification?

Answer 6

Magnification is how many times larger the image is than the actual size of object being viewed.

Question 7

How do you calculate magnification?

Answer 7

Size of object/actual side of object

Image/Actual

Question 8

How many micrometers in 1 millimetre?

Answer 8

1000

Question 9

How many nanometers in 1 micrometer?

Answer 9

1000

Question 10

What is electron microscopy?

Answer 10

• Where a microscope employs a beam of electrons to illuminate the specimen.
• Produces black and white images

Question 11

What are the two types of electron microscope?

Answer 11

Transmission electron microscope, scanning electron microscope

Question 12

What is a transmission electron microscope?

Answer 12

• A microscope where a beam of electrons is transmitted through specimen and focused to produce image.
• Best resolution (better than SEM) with resolving power of 0.5nm.

Question 13

What is a scanning electron microscope?

Answer 13

• A microscope where a beam of electrons is sent across surface of specimen and reflected electrons are collected.
• Resolving power from 3-10nm.
• Produces 3D images

Question 14

What is a laser scanning confocal microscope?

Answer 14

A microscope that employs a laser beam and a pin-hole aperture to produce an image with a very high resolution.
- Used in diagnosis of diseases in eyes

Question 15

What is the nucleus?

Answer 15

• The nucleus contains coded genetic information in the form of DNA molecules.
• DNA directs the synthesis of proteins required by the cell.
• Controls metabolic activities of the cell

Question 16

What does the nuclear envelope & pore do?

Answer 16

• The nuclear envelope protects the DNA from damage in cytoplasm.
• The nuclear pores allow RNA molecules to leave the nucleus for protein synthesis

Question 17

What is the nucleolus?

Answer 17

• An area within the nucleus and is responsible for producing ribosomes.

Question 18

What are mitochondria?

Answer 18

• The site of cellular respiration
• Has a double membrane
• Inner membrane folded to form cristae
• The fluid is called the matrix

Question 19

What are vesicles?

Answer 19

Membranous sacs that are used to transport materials in the cell

Question 20

What are lysosomes?

Answer 20

• Specialised forms of vesicles that contain hydrolytic enzymes.
• Responsible for breaking down waste material in cells, even old organelles
• Plays an important role in immune system as they are responsible for breaking own pathogens.

Question 21

What is the cytoskeleton?

Answer 21

• A network of fibres necessary for the shape and stability of a cell.
• Responsible for cell movement, cell contraction. movement of organelles

Question 22

What are the three components of a cytoskeleton?

Answer 22

1) Microfilaments- Made from protein called actin. Responsible for cell movement and contraction during cytokinesis
2) Microtubules- Determines shape of the cell, spindle fibres are made from microtubules, track movement or organelles around cell
3) Intermediate fibres- These fibres give mechanical strength to cells and help maintain their integrity.

Question 23

What are centrioles?

Answer 23

• Component of the cytoskeleton composed of microtubules

Question 24

What is endoplasmic reticulum?

Answer 24

A network of membranes enclosing flattened sacs called cisternae, connected to the outer membrane of the nucleus.

Question 25

What are the two types of endoplasmic reticulum?

Answer 25

Smooth ER & rough ER

Question 26

What is smooth ER?

Answer 26

It is responsible for lipid and carbohydrate synthesis, and storage

Question 27

What is rough ER?

Answer 27

It has ribosomes bound to the surface and is responsible for the synthesis and transport of proteins.

Question 28

What are ribosomes?

Answer 28

- Ribosomes are either free floating in the cytoplasm or attached to the ER. - Constructed of RNA molecules - Site of protein synthesis

Question 29

What is the golgi apparatus?

Answer 29

- A compact structure formed of cistarnae and does not contain ribosomes. - Plays a role in modifying and packaging proteins into vesicles.

Question 30

Describe the protein production.

Answer 30

1) Proteins are synthesised on the ribosome bound to the endoplasmic reticulum. 2) They pass into the cisternae and are packaged into transport vesicles. 3) Vesicles containing the newly synthesised proteins move towards the Golgi apparatus via the cytoskeleton. 4) The vesicles fuse with the cis face of the Golgi apparatus and the proteins enter. They are structurally modified before leaving the Golgi apparatus in vesicles from the trans face. 5) Secretory vesicles carry the proteins that are to be released from the cell. 6) The vesicles fuse with the cell surface membrane releasing the contents by exocytosis.

Question 31

What are vacuoles?

Answer 31

- Vacuoles are membrane lined sacs in the cytoplasm containing cell sap. - The membrane of the vacuole is called the tonoplast. - The tonoplast is selectively permeable.

Question 32

What are chloroplasts?

Answer 32

- Chloroplasts are the organelles responsible for photosynthesis in plant cells. - Have a double membrane. - The fluid enclosed is called the stroma. - They have a network of flattened sacs called thylakoids. - Several thylakoids stacked together are called a granum.

Question 33

What is the magnification of electron microscopes?

Answer 33

Over 500 000

Question 34

What is the magnification of light microscopes?

Answer 34

Up to 2000 magnification

Question 35

What is the resolving power for light microscopes?

Answer 35

200nm

Question 36

What is the resolving power for electron microscopes?

Answer 36

TEM- 0.5nm | SEM- 3-10nm