✅ 1.1 Cell Biology

Question 1

Convert 1mm into micrometres

Answer 1

1 mm = 1000 μm

Question 2

Convert 1μm into nanometres

Answer 2

1μm = 1000 nm

Question 3

What is the function of the nucleus?

Answer 3

• Controls the cell’s activities
• It contains chromosomes that are made up of genetic material that carry the instructions for making protein and cell growth

Question 4

What is a Cytoplasm?

Answer 4

A jelly-like substance where most of the chemical reactions needed for life take place

Question 5

What is the function of the Cell Membrane?

Answer 5

Partially permeable structure that controls what goes in and out of the cell

Question 6

What happens inside the Mitochondria?

Answer 6

The mitochondria is where aerobic respiration takes place, to release energy for the cell

Question 7

What is the function of Ribosomes?

Answer 7

Ribosomes are where proteins are synthesised

Question 8

Extra sub-cellular structures inside a plant cell

Answer 8

• Permanent Vacuole
• Cell Wall
• Chloroplasts

Question 9

What is the function of the Permanent Vacuole

Answer 9

The permanent vacuole is filled with cell sap that stores nutrients and supports the cell by keeping it rigid

Question 10

What is the function of the Cell Wall?

Answer 10

Made of cellulose, which strengthens the cell

Question 11

What is the function of chloroplasts?

Answer 11

Chloroplasts contain chlorophyll that absorbs light energy to carry out photosynthesis

Question 12

Where are eukaryotic cells found?

Answer 12

Eukaryotic cells are found in Animal, Plant and Fungal cells

Question 13

Propeties of Eukaryotic Cells

Sub-Cellular structures, Size

Answer 13

• Have a cell membrane, cytoplasm and nucleus
• 5 - 100μm in size

Question 14

Where are prokaryotic cells found?

& describe their size

Answer 14

• Found in Bacteria
• Much smaller than eukaryotic cells
• 0.2 - 2μm in size

Question 15

What sub-cellular structures do eukaryotic& prokaryotic cells have in common?

Answer 15

• Cell membrane
• Cytoplasm
• Ribosomes
• Cell wall (with plants)

Question 16

What sub-cellular structures are not in prokaryotic cells?

Answer 16

Prokaryotic cells have no nucleus, mitochondria or chloroplasts

Question 17

Where is the genetic material in a prokaryotic cell found?

Answer 17

The genetic material is enclosed in a single DNA loop in the cytoplasm

Question 18

What are Plasmids?

Answer 18

Plasmids are extra small rings of DNA

Question 19

What is the function of Plasmids?

Answer 19

Plasmids have genes that can replicate and move between cells so that genetic information can be shared

Question 20

Which two cells have a cell wall made of cellulose?

Answer 20

Plant cells and Algal cells have a cell wall made of cellulose

Question 21

What do specialised cells do?

Answer 21

They carry out a particular function

Question 22

Examples of Specialised Cells

Answer 22

Animals:
- Sperm Cell
- Nerve Cell (Neurone)
- Muscle Cell

Plants:
- Root Hair Cell
- Xylem
- Phloem

Question 23

Sperm Cell

Answer 23

Question 24

Nerve Cell

Answer 24

• Axon is long to carry impulses across the body
• Dendrites make connections with other cells

Question 25

Root Hair Cell

Answer 25

• Long thin projections increase the surface area for absorption
• Many mitochondria to provide energy for active transport

Question 26

Xylem and Phloem

Answer 26

Phloem:

• Elongated cells to transport sugars over long distances
• Have many mitochondria for active transport

Xylem:

• Lignin in walls to provide strength and support
• Hollow tubes with no end walls to allow water and minerals to flow easily

Question 27

When do most animal cells differentiate?

Answer 27

Most animal cells differentiate at an early stage

Question 28

Why do animal cells differentiate?

& how?

Answer 28

Animal cells differentiate to form different types of specialised cells to carry out a certain functions, by developing different sub-cellular structures

Question 29

How is cell division restricted in mature animals?

Answer 29

Cell divison is restricted to replacement and repair

Question 30

When and how do plant cells differentiate?

Answer 30

Plant cells have the ability to differentiate throughout their lives through the meristems

Question 31

Give an example of differentiation in animals

Answer 31

From an early embryo to a specialised cell

Question 32

PRACTICAL

How do we prepare the slide before using the microscope?

Preparing the Slide

Answer 32

1. Put a small drop of water on the slide
2. Place a tissue sample on the slide
3. Add a few drops of iodine solution the stain the cells
4. Lower a coverslip onto the tissue using a mounted needle to prevent air bubbles

Question 33

PRACTICAL

How do we use a Light Microscope

After preparing the slide

Answer 33

1. Place the slide on the microscope stage
2. Look through the eyepiece and use the lowest power objective lens to find the cells
3. Use the coarse adjustment knob to focus on the cells
4. Use the fine adjustment knob to focus more clearly
5. Switch to a higher power lens and use only the fine adjustment knob to focus

Question 34

What is Magnification?

Answer 34

Magnification is how many times larger an image is seen through a microscope compated to the actual object

Question 35

Formula for Magnification

Answer 35

Magnification = size of image / size of real object

Question 36

What is Resolution

Answer 36

The ability to see or distinguish two or more points as separate points

Question 37

Differences between the electron microscope and light microscope
What are the benefits?

Answer 37

• The electron microscope has a higher magnification and resolving power than the light microscope
• This has allowed us to see sub-cellular structures in finer detail

Question 38

Bacteria multiply through binary fission
What is binary fission?

Answer 38

Binary fission is when one bacterial cell divides into two

Question 39

How often can bacteria multiple in the best conditions?

Answer 39

Once every 20 minutes