Cell Biology

Question 1

What are the organelles in a plant cell?

Answer 1

Cell wall, cell membrane, ribosomes, mitochondria, chloroplasts, cytoplasm, nucleus, vacuole

Question 2

What are the organelles in an animal cell?

Answer 2

Cell membrane, ribosomes, mitochondria, cytoplasm, nucleus

Question 3

What are the differences between eukaryotic and prokaryotic cells?

Answer 3

Eukaryotic cells have a nucleus and are multicellular and prokaryotic cells have a circular strand of DNA and are unicellular

Question 4

What is the definition of magnification?

Answer 4

The aparent enlargement of an object

Question 5

What is the definition of resolution?

Answer 5

The fineness of detail that can be seen in an image

Question 6

What is the calculation for magnification?

Answer 6

Image = magnification x actual size

Question 7

Advantages and disadvantages of light microscopes

Answer 7

Advantages
- cheap
- easy to use
- can magnify living cells or small organisms

Disadvantages
- requires a stain
- can’t see very small organelles

Question 8

Advantages and disadvantages of electron microscopes

Answer 8

Advantages
- allows the observation of smaller organelles

Disadvantages
- can’t observe living organisms
- very expensive

Question 9

What is a stem cell?

Answer 9

An undifferentiated cell that can multiply into other undifferentiated cells or differentiate into many other specialised cells

Question 10

What are the two kinds of human stem cell?

Answer 10

Embryonic (from embryos) and adult (from certain places like bone marrow)

Question 11

Which can differentiate into more kinds of specialised cells - embryonic or adult?

Answer 11

Embryonic

Question 12

What is therapeutic cloning?

Answer 12

The process where an embryo can be made to have the same genetic information as the patient so the stem cell won’t be rejected

Question 13

Where are stem cells found in plants?

Answer 13

The meristem (the roots and shoots of the plant)

Question 14

What are the uses of stem cells in plants?

Answer 14

• Rare species of plant can be cloned to prevent extinction
• Crop plants with special features (e.g. resistance to disease) can be cloned

Question 15

What is diffusion?

Answer 15

The net movement of particles from an area of high to low concentration down a concentration gradient

Question 16

What is osmosis?

Answer 16

The diffusion of water; the net movement of water molecules from an area of high to low concentration down a concentration gradient through partially permeable membrane

Question 17

What are the factors that affect the rate of diffusion?

Answer 17

Temperature - increased temperature increases the rate of diffusion
Concentration gradient - a steeper gradient increases the rate of diffusion
Surface area - increased surface area increases the rate of diffusion

Question 18

What is an isotonic solution?

Answer 18

Any solution that has the same water concentration as the cells

Question 19

What is a hypertonic solution?

Answer 19

A solution with a low water concentration; a cell placed in the solution will lose water by osmosis and shrink (a flaccid cell)

Question 20

What is a hypotonic solution?

Answer 20

A solution with a high water concentration; a cell placed in the solution will have water move into it by osmosis, causing the cell to eventually burst (a turgid cell)

Question 21

What are the differences between xylem and phloem cells?

Answer 21

Xylem is made of dead tissue and transports water and minerals (transpiration) one way through the plant - roots to shoots
Phloem is made of living tissue and transports glucose (translocation) in both directions around the plant

Question 22

What is active transport?

Answer 22

The opposite of diffusion; moving from an area of low to high concentration against a concentration gradient

Question 23

What does the rate of active transport depend on?

Answer 23

The rate of respiration

Question 24

When is active transport used in plants?

Answer 24

When the concentration of minerals in the soil is lower than inside the plant, active transport is used to absorb the minerals against the concentration gradient

Question 25

How are sperm cells adapted to their function?

Answer 25

Long tail that makes it easier to swim; they are also streamlined which makes it easier to swim
Have lots of mitochondria which provide the energy needed for swimming
Contain enzymes that allow them to fertilise the egg easier by digesting the outer layer

Question 26

How are muscle cells adapted for their function?

Answer 26

Contain protein fibres that change their length for contractions
Have lots of mitochondria to provide energy for contractions