B1.1 cell structure

Question 1

How are Light Microscopes used to view cells with staining

Answer 1

1. Use scissors to cut a small sample of the tissue
2. Peel or cut a thin layer of cells from the sample and place onto the slide using tweezers
3. Some samples will need to be treated with chemicals to kill/make it rigid
4. Place a coverslip on top and press down to remove air bubbles
5. A stain may be used to make the structures visible (methylene blue for cheek cells and iodine for onion)
6. Adding a few drops of water to the slide can prevent the cells from becoming dehydrated

Question 2

How to calculate magnification of an object?

Answer 2

Image size/object size

Question 3

How to calculate magnification of a microscope?

Answer 3

magnification of eyepiece lens x magnification of the objective lens

Question 4

What are the advantages of a light microscope?

Answer 4

• cheap
• can be used on living specimens
• doesn’t require training

Question 5

what are the disadvantages of a light microscope?

Answer 5

• low resolution
• low magnification strength
• staining is required for some samples

Question 6

What is the difference between Eukaryotes and Prokaryotes?

Answer 6

Eukaryotes can be unicellular or multicellular whereas prokaryotes can only be unicellular and are much smaller

Question 7

What subcellular structures do prokaryotic cells contain?

Answer 7

• cytoplasm
• cell membrane
• cell wall
• circular DNA loop
• plasmid
• ribosome

Question 8

What sub cellular structures do animal cells contain?

Answer 8

• nucleus
• cytoplasm
• cell membrane
• mitochondria
• ribosomes

Question 9

what sub cellular structures do plants have that animals don’t have?

Answer 9

• chloroplasts
• vacuole
• cell wall

Question 10

what is the function of the nucleus?

Answer 10

contains genetic material which codes for a particular protein

Question 11

what is the function of the cytoplasm?

Answer 11

• site of chemical reactions
• contains enzymes that speed up reactions

Question 12

what is the function of the cell membrane?

Answer 12

• contains receptor molecules which identify and control what enters and leaves the cell

Question 13

what is the function of the mitochondria?

Answer 13

• where aerobic respiration reactions occur, providing energy

Question 14

what is the function of ribosomes?

Answer 14

• site of protein synthesis

Question 15

what is the function of the chloroplasts?

Answer 15

• where photosynthesis takes place
• contains chlorophyll which harvests the light needed for photosynthesis

Question 16

what is the function of the vacuole?

Answer 16

• contains cell sap
• improves cell rigidity

Question 17

what is the function of the cell wall?

Answer 17

• made of cellulose which provides strength to the cell

Question 18

what are plasmids?

Answer 18

small rings of DNA

Question 19

How are electrons microscopes different to light microscopes?

Answer 19

Electron microscopes use electrons to form images, and allow scientists to view smaller structures

Question 20

what are the two types of electron microscopes?

Answer 20

• scanning electron microscope
• transmission electron microscope

Question 21

what are the advantages of electron microscopes?

Answer 21

• produces 3D images
• can view smaller organelles

Question 22

what are the disadvantages of electron microscopes?

Answer 22

• expensive
• samples can only be dead
• very large
• requires training