Cell structure and Principles of Organisation - done

Question 1

What are the components of animal cells (5)

Answer 1

• nucleus
• cytoplasm
• cell membrane
• mitrochondria
• ribosomes

Question 2

What are the components of plant cells (5)

Answer 2

• nucleus
• cytoplasm
• cell membrane
• mitrochondria
• ribosomes
• cell wall
• permanent vacuole
• chloroplasts

Question 3

What are the uses of a nucleus?

Answer 3

Stores cell information in the form of DNA
Controls the activity of the cell
Controls metabolism

Question 4

What does cytoplasm do?

Answer 4

Jelly-like fluid
Contains enzymes
Helps with photosynthesis

Question 5

What does the cell-membrane do?

Answer 5

Permeable to only water and gases
Controls what enters and leaves cell

Question 6

What does mitochondria do?

Answer 6

The place where oxygen is used to break glucose down into CO2 and H20 and energy
Where areobic respiration occurs

Question 7

What do ribosomes do?

Answer 7

proteinsynthesis

Question 8

What do chloroplasts do?

Answer 8

Absorb sunlight
Sight of photosynthesis
Contains chlotophyll

Question 9

What does the cell wall do?

Answer 9

Supports/protects the cell
Resists entry of excess water
Slightly stretchy which keeps cell from bursting

Question 10

What is the cell membrane made of?

Answer 10

Made of protein and fat

Question 11

What is the cell wall made of?

Answer 11

Made of cellulose

Question 12

What does the permanent vacuole do?

Answer 12

Stores water
Membrane-bound bodies of liquid cell sap

Question 13

What are eukaryotic cells - components (3) ?
Examples of eukaryotic cells? (4)

Answer 13

Cells that have a cell membrane, cytoplasm and genetic material enclosed in a nucleus.
Example:
animals , plants, fungi, protista

Question 14

What are prokaryotic cells - components (2)
Example of prokaryotic cell?

Answer 14

Components:
- single DNA loop - plasmids - found free in the cytoplasm (not enclosed in a nucleus)
- cell wall
Example: bacteria

Question 15

Which is bigger prokaryotic or eukaryotic cells?

Answer 15

eukaryotic

Question 16

How are red blood cells specialised and what do they do? (3)

Answer 16

• Carry oxygen around your body
• No nucleus
• Biconcave disc shape which gives a large surface area for absorbing oxygen

Question 17

How are epithelial cells specialised and what do they do? (2)

Answer 17

• line the mouth and other parts of body
• Flat and fit together

Question 18

How are nerve cells specialised and what do they do?
(5)

Answer 18

Carry electrical impulses around the body
- Lots of dentries to make connections to other nerve cells
- Axon (that carries the nerve impulse) are very long
- Has a special transmitter chemical
- Contains lots of mitochondria to provide energy

Question 19

How are sperm cells specialised and what do they do? (4)

Answer 19

Function: contain genetic information of the male parent
- Long tail that moves to help move the sperm through the water/female reproductive system
- Middle section is full of mitochondria to transfer energy needed for the tale to work
- Stores digestive enzymes for breaking down the outer layers of the egg

Question 20

How are muscle cells specialised and what do they do?
(2 uses, 4 adaptations)

Answer 20

They contract and relax in pairs to move the bones of the skeleton. Smooth muscle cells form one of the layers of tissue in your digestive system and contract to squeeze the food through the gut
- Long
- Special proteins that slide over each other making fibers contract
- Mitochondria to transfer energy for the chemical reactions that take place as they contract and relax)
- Store glycogen

Question 21

How are root hair cells specialised and what do they do? (4)

Answer 21

Absorb water/minerals for plants
- Large permanent vacuole - speeds up movement of water by osmosis from soil across root hair cell - maintain potential gradient
- Have many mitochondria that transfer the energy needed for active transport of mineral ions into root hair cells
- Thin walls = short diffusion distance

Question 22

How are xylem cells specialised and what do they do? (4)

Answer 22

Transports water and mineral ions from the roots to the highest leaves/shoots.
Supports plant
- Alive when the first form but lignin build up in spirals in the cell walls. Cells die and form long hollow tubes - allow water/mineral ions to move through them easily
- Rings of lignin make them strong and help them withstand the pressure of water moving up.

Question 23

How are phloem cells specialised and what do they do? (4)

Answer 23

Carries the food made by photosynthesis around the body of the plant
- Made of phloem cells that form hollow tubes
- Lose a lot of their internal structure but they are supported by companion cells
- Companion cells have mitochondria that transfer energy

Question 24

What is the difference between a cell, a tissue, an organ and an organ system?

Answer 24

Cells are the basic building blocks of all living organisms.

A tissue is a group of identical cells with a similar structure and function.

Organs are aggregations of different tissues performing specific functions.

Organs are organised into organ systems, which work together to form organisms.

Question 25

What is cell differentiation?

Answer 25

Process by which a cell changes to become specialised

Question 26

What happens when a cell differentiates?

Answer 26

It develops a structure and composition of subcellular structures which enables it to carry out a certain function

Question 27

When do cells differentiate in an animal and why?

Answer 27

Early stage of its development.
Cell division is mainly restricted to repair and replacement in mature animals. Animal cells therefore lose their ability to differentiate when matured

Some cells throughout the body of an animal retain the ability to differentiate throughout the life of the animal. These cells are called ADULT STEM CELLS and are mainly involved in replacing and repairing cells (such as blood or skin cells)

Question 28

When do cells differentiate in a plant?

Answer 28

Many types of plant cell retain the ability to fully differentiate throughout the life of a plant, not just in the early stages of development

Question 29

How do light microscopes work? (2)

Answer 29

Use light and lenses to form a magnified image of a specimen.
Possible to see images of cells and large subcellular structures (like nuclei and vacuoles), although stains are often required to highlight certain parts of cells

Question 30

How do electron microscopes work? (2)

Answer 30

Electron microscopes use beams of electrons, rather than light,

Question 31

Difference between electron and light microscopes?

Answer 31

An electron microscope has much higher magnification and resolving power than a light microscope
It can be used to study cells in much finer detail. This has enabled biologists to see and understand many more sub-cellular structures.

Question 32

How to find magnification?

Answer 32

Magnification = image size / actual size

Question 33

How to culture microorganisms?

Answer 33

1. Glass Petri dishes and agar gel must be sterilised before use in an autoclave, or pre-sterilised plastic Petri dishes can be bought (this will kill any bacteria that are present in the solution or on the Petri dishes)
2. Pour the sterile agar plates and allow to set fully ( provides the selected bacterium with all the nutrients needed to grow)
3. Sterilise the inoculating loop, by heating it in the Bunsen burner flame. (kills any bacteria that are present on the loop)
4. Dip the inoculation loop into the microorganism solution and make streaks on the surface of the agar plate. (this allows the bacteria to spread out and to grow in individual colonies on the agar plate)
5. Replace the lid as soon as possible, secure with tape. Label and invert the plate, and store upside down (this stops additional unwanted bacteria in the air contaminating the plate. Do not fully seal the lid, as this will stop oxygen reaching the bacterium, and this may encourage harmful anaerobic bacteria to grow)
6. Incubate at a maximum temperature of 25°C in schools and colleges (this reduces the chance of growing harmful pathogens. Hospital laboratories would incubate plates at 37°C (body temperature) to allow quick growth and identification)

Question 34

How do bacteria multiply?

Answer 34

Simple cell division known as binary fission

Question 35

Why should the Bunsen burner always be on when culturing microorganisms?

Answer 35

The flame creates a convection current above the bench, preventing contamination of any microorganisms in the air)

Question 36

How to calculate inhibition zone?

Answer 36

3.14 (pie) * r^2 (squared)

Question 37

What is the inhibition zone?

Answer 37

Circular area around the spot of the antibiotic in which the bacteria colonies do not grow