Cell Biology

Question 1

Name the two main types of cell?

Answer 1

Prokaryotic, eukaryotic

Question 2

Name the two main types of eukaryotes

Answer 2

Plants, animals

Question 3

Name 3 organelles ALL eukaryotes have.

Answer 3

Cell membrane, cytoplasm, nucleus

Question 4

Name three organelles prokaryotic cells ALWAYS have

Answer 4

Cell membrane, cytoplasm, cell wall

Question 5

How is DNA stored in prokaryotic cells?

Answer 5

All DNA is found in a single loop, and there may be one or more smaller rings or DNA called plasmids.

Question 6

What do nuclei do, and what does it contain?

Answer 6

They contain DNA which controls the cell

Question 7

What do cell membranes do?

Answer 7

They control what enters and leaves the cell

Question 8

What do mitochondria do and what do they contain?

Answer 8

They contain enzymes that allow aerobic respiration to occur

Question 9

What do chloroplasts do and what do they contain?

Answer 9

They contain enzymes and chlorophyll that allow photosynthesis to occur

Question 10

What do plasmids do and what do they contain?

Answer 10

They contain DNA that enhances the survival of an organism.

Question 11

What do cells walls do and what do they contain?

Answer 11

They contain cellulose that strengthens the cell.

Question 12

What does cytoplasm do and what does it contain?

Answer 12

It contains enzymes which allow chemical reactions to take place in the cell

Question 13

What do ribosomes do and what do they contain?

Answer 13

They contain enzymes which allow protein synthesis to occur

Question 14

What 5 organelles do most animal cells contain?

Answer 14

Nucleus, Cytoplasm, Cell Membrane, Mitochondria, Ribosomes

Question 15

What 3 organelles do plants often have that animal cells don’t.

Answer 15

Chloroplasts, Permanent Vacuole, Cell Wall

Question 16

How are sperm cells adapted to their function?

Answer 16

They have an acrosome which contains enzymes which break down an egg’s wall. They also contain half the amount of chromosomes in the nucleus so that when it fertilises an egg the embryo has one full set of DNA. They contain many mitochondria to provide the cell with enough energy to swim towards the egg, and they a flagellum which makes the cell streamlined so it can swim to the egg faster.

Question 17

How are nerve cells adapted to their function?

Answer 17

They have a long thin axon, which allows electrical signals to travel very fast without hitting a synapse. They have an insulating myelin sheath which makes the signal travel faster, and they have many dendrites so they can receive signals from many cells.

Question 18

How are muscle cells adapted to their function?

Answer 18

They are long so can slide over each other easily. They contain lots of mitochondria so the cell has enough energy to contract to cause movement. They contain glycogen which can be converted to glucose for respiration so the cell can contract to cause movement.

Question 19

How are root hair cells adapted to their function? Explain four ways.

Answer 19

They have a large protrusion which increases surface area so diffusion and osmosis is faster. They have a large permanent vacuole that stores water so there is a larger water concentration gradient for osmosis. They have many mitochondria to provide energy for active transport. They have no chloroplasts to make room for other organelles and because there is no light for photosynthesis underground.

Question 20

How are xylem cells adapted to their functions? Explain three ways.

Answer 20

They are hollow which allows them to transport water up and down the cell. They contain lignin which strengthens the cell so they can withstand water pressure, and they are dead so they do not use up unnecessary nutrients.

Question 21

How are phloem cells adapted to their function? Explain two ways.

Answer 21

They have sieve plates which allows them to form tubes which sugar can be transported. They also have almost no organelles so that there is more room for dissolved substances to be transported. This means that the cell must have companion cells to provide it with nutrients.

Question 22

Explain the importance of cell differentiation.

Answer 22

It allows unspecialised stem cells to become specialised cells, and it allows cells to perform specific functions. This makes it important for growth and development of embryos and seedlings, and for repair of blood and plant tissue.

Question 23

Explain what happens during cell differentiation?

Answer 23

It acquires different sub-cellular structures to enable it to carry out a certain function.

Question 24

How have microscopy techniques developed over time?

Answer 24

Light microscopes were invented hundreds of years ago. Light microscopes have developed to be easier to use and have a higher magnification. The invention of electron microscopes increased magnification and resolution.

Question 25

What equation links image size, magnification and real size?

Answer 25

Magnification = image size / real size

Question 26

Briefly, what happens in the cell cycle?

Answer 26

The genetic material is doubled and then the cell divides into two identical cells.

Question 27

What happens during mitosis?

Answer 27

One set of chromosomes is pulled to each end of the cell and the nucleus divides.

Question 28

What is a stem cell?

Answer 28

An undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.

Question 29

Describe the function of stem cells in embryos.

Answer 29

They can divide and can differentiate into most types of human cells, allowing growth and development.

Question 30

Name two diseases that could be cured by stem cells.

Answer 30

Diabetes and paralysis

Question 31

What is diffusion?

Answer 31

Diffusion is the spreading out of the particles in a substance in solution or in a gas, resulting in a net movement from an area of high concentration to an area of low concentration.

Question 32

Explain three factors that affect the rate of diffusion.

Answer 32

A higher concentration gradient increases the rate of diffusion because there are many particles that can move to a lower concentration while there are no particles that could do the reverse, so the net movement is faster. A higher temperature leads to diffusion occurring faster since this means particles have more energy so the movement of particles is faster. A higher surface area of a membrane means that there are more places where diffusion can occur across, so diffusion happens faster.

Question 33

What is osmosis?

Answer 33

The diffusion of water from an area of high water concentration to an area of low concentration gradient through a partially permeable membrane.

Question 34

What is active transport?

Answer 34

The movement of substances from an area of low concentration to an area of high concentration against a concentration gradient, which requires energy from respiration.