B1 - Cell Structure And Organisation

Question 1

E. Magnification

Answer 1

Magnification= image size / size of real object

Question 2

Function of cytoplasm?

Answer 2

Liquid gel where organisms are suspended and most chemical reactions for life take place.

Question 3

Function of ribosomes?

Answer 3

Site of protein synthesis

Question 4

Function of mitochondria?

Answer 4

Site of aerobic respiration

Question 5

Function of cell membrane?

Answer 5

Controls the passage of substances in and out of the cell.

Question 6

Function of chlorophyll?

Answer 6

Absorbs light so plant can make food by photosynthesis

Question 7

Give a feature of a eukaryotic cell

Answer 7

Genetic material is enclosed in a nucleus

Question 8

Give a feature of a prokaryotic cell

similar to the eukaryotic cell feature

Answer 8

Genetic material is not enclosed in a nucleus (free floating in the cytoplasm).

Question 9

What are plasmids?

Answer 9

Small rings of DNA that code for specific features such as antibiotic resistances

Question 10

Bacteria are….

Answer 10

Prokaryotic cells

Question 11

Examples of specialised cells?

Answer 11

Nerve cells, muscle cells, sperm cells, red blood cells, ciliated epithelial cells, root hair cells etc etc

Question 12

How are nerve cells specialised? (3)

Answer 12

• Lots of dendrites that make connections to other cells
• Axons that carry the impulse from one place to another
• Synapses are adapted to pass the impulse to another cell or between a nerve cell and a muscle cell

Question 13

How are muscle cells specialised? (3)

Answer 13

• Contain proteins that slide over each other and make the fibres contract
• Contain many mitochondria to provide the energy needed for chemical reactions to take place
• Store glycogen, which can be broken down and used in cellular respiration by the mitochondria to provide energy needed for the fibres to contract.

Question 14

How are sperm cells specialised?

4

Answer 14

• Long tail helps it to move
• Middle section is full of mitochondria, which provide energy for the tail
• Large nucleus contains genetic information to be passed on
• Acrosome stores digestive enzymes to break down the outer layers of the egg

Question 15

Specialised plant cells?

Answer 15

Root hair cells, photosynthetic cells, xylem cells and phloem cells

Question 16

How are root hair cells specialised? (3)

Answer 16

• Long and narrow, which increases the surface area for water to move into the cell
• Permanent vacuole that speeds up movement of water by osmosis from the soil across the root hair cell
• Many mitochondria to transfer energy needed for active transport of mineral ions into the cells

Question 17

How are photosynthetic cells specialised? (3)

Answer 17

• Contain specialised chloroplasts containing chlorophyll which absorbs the sunlight needed for photosynthesis
• Usually positioned in continuous layers in the leaves and outer layers of the stem so they absorb as much light as possible
• Large perm vacuole that keeps the cell rigid as a result of osmosis when lots of these rigid cells are arranged together, they help support the stem.

Question 18

How are xylem cells specialised? (2)

Answer 18

• Alive at first but die and form long hollow tubes to allow water and mineral ions to move easily through them
• Spirals and rings of lignin make them very strong and help them to withstand pressure of water.

Question 19

How are phloem cells specialised? (2)

Answer 19

• Call walls between the cells break down to form special sieve plates. Allow water carrying dissolved food to move freely
• Supported by companion cells which transfer energy and support them.

Question 20

D. Diffusion

Answer 20

The spreading out of the particles of gas of any substance in a solution ( a solute)

Question 21

Net movement of diffusion ?

Answer 21

From high to low concentration, down the conc gradient

Question 22

What effects the rate of diffusion?

Answer 22

Difference in concentrations, the temperature and the available surface area

Question 23

How do substances such as urea and glucose and gases such as oxygen and carbon dioxide move out and into cells?

Answer 23

Diffusion

Question 24

D. Osmosis?

Answer 24

The movement of water to dilute a solution across a partially permeable membrane, Down the conc gradient

Question 25

D. Isotonic?

Answer 25

The concentration of the solution is the same inside and outside the cell

Question 26

D. Hypertonic?

Answer 26

Solution conc is higher OUTSIDE the cell

Question 27

D. Hypotonic

Answer 27

Conc of solution is higher INSIDE the cell

Question 28

Why is osmosis important in plants?

Answer 28

To maintain turgor ( turgidity )

Question 29

Plasmolysis?

Answer 29

When the vacuole and cytoplasm shrink and the cell membrane is pulled away from cell wall

Question 30

D. Active transport?

Answer 30

The movement of substances from a dilute solution to a more concentrated solution against the concentration gradient

Question 31

Where does active transport occur? (2)

Answer 31

• Small intestine - uptake of sugar

* In the roots (root hair cells)

Question 32

As the object gets bigger…

Answer 32

The surface area:volume ration decreases

Question 33

Why do most exchange surfaces usually have a large SA and thin walls?

Answer 33

To give a short diffusion distance.

Question 34

Differences between prokaryotes and eukaryotes? (3)

Answer 34

pro’s are….

• smaller
• don’t have a nucleus
• may have plasmids