Topic 1 - Cell Biology

Question 1

Cells can be either _______ or _______.

Answer 1

prokaryotic, eukaryotic

Question 2

What is the difference between eukaryotic cells and prokaryotic cells?

Answer 2

Eukaryotic cells are complex - include animal and plant cells.
Prokaryotic cells smaller and simpler - bacterial ones.

Question 3

What is the difference between a eukaryote and a prokaryote?

Answer 3

Eukaryotes - organisms made from eukaryotic cells.

Prokaryotes - organisms made form prokaryotic cells.

Question 4

Name the 5 parts of an animal cell.

Answer 4

Nucleus, cytoplasm, mitochondria, ribosomes, cell membrane.

Question 5

Name the 8 parts of a plant cell.

Answer 5

Nucleus, cytoplasm, mitochondria, ribosomes, cell membrane, rigid cell wall, permanent vacuole, chloroplasts.

Question 6

What does the nucleus do?

Answer 6

It has genetic material that controls activities of the cell.

Question 7

What is cytoplasm?

Answer 7

A gel-like substance - where most of the chemical reactions take place.

Question 8

What is mitochondria?

Answer 8

Where most of the reactions take place for aerobic respiration.

Question 9

What are ribosomes?

Answer 9

Where proteins are made in the cell.

Question 10

What is the rigid cell wall?

Answer 10

Made of cellulose - supports cell and strengthens it.

Question 11

What is the permanent vacuole?

Answer 11

Has cell sap, a solution of sugar and salts.

Question 12

What are chloroplasts?

Answer 12

Where photosynthesis occurs - makes food for the plant.

Contains chlorophyll, absorbs light needed for photosynthesis.

Question 13

What are the 5 parts of a bacterium?

Answer 13

Cell membrane, cell wall, cytoplasm, plasmids, strand of DNA floating freely in the cytoplasm.

Question 14

What is the magnification formula?

Answer 14

magnification = image size/real size

Question 15

What do light microscopes do?

Answer 15

Use light and lenses to look at individual cells and large subcellular structures like the nucleus.

Question 16

What do electron microscopes do?

Answer 16

Use electrons, higher magnification. Smaller things in more detail.

Question 17

What is a microscope slide?

Answer 17

Glass or plastic in which a specimen is mounted.

Question 18

What is differentiation?

Answer 18

Where a cell changes to become specialised for its job.

Question 19

When does differentiation mostly occur?

Answer 19

As an organism develops.

Question 20

When do most animals and plants lose the ability to differentiate?

Answer 20

Animals - at an early stage of development.

Plants - never.

Question 21

What are undifferentiated cells called?

Answer 21

Stem cells.

Question 22

How are sperm cells specialised?

Answer 22

Long tail, streamlined head to help swim, mitochondria provide energy, enzymes in head to get through egg cell membrane.

Question 23

How are nerve cells specialised?

Answer 23

Long, branched connections, form a network.

Question 24

How are muscle cells specialised?

Answer 24

Long so space to contract, lots of mitochondria for energy used for contraction.

Question 25

How are root hair cells specialised?

Answer 25

On surface of plant roots, long hairs stick out in soil big surface area to absorb water and mineral ions, long.

Question 26

How are xylem and phloem tubes specialised?

Answer 26

Cells long, joined end to end. Xylem are hollow, phloem have very few sub-cellular structures so things move quickly through them.

Question 27

What are chromosomes?

Answer 27

Coiled up lengths of DNA molecules. Each one contains a large quantity of genes.

Question 28

What do genes do?

Answer 28

Control characteristic development.

Question 29

How many chromosomes do humans have?

Answer 29

46 (23 pairs). 23 from father and 23 from mother. 2 copies of each chromosome, one is father and one is mother.

Question 30

What are the 3 stages prior to mitosis?

Answer 30

1) If the cell isn’t dividing, DNA is spread out in long strings.
2) Before it divides, it grows to increase sub-cellular structures.
3) DNA duplicated - one copy for each new cell – Forms x shaped chromosomes – two duplicate arms.

Question 31

What are the 3 stages of mitosis?

Answer 31

4) Chromosomes line up at centre of the cell. Cell fibres pull them apart. Two arms go to opposite ends.
5) Membranes from around the two sets of chromosomes become the nuclei - nucleus divided.
6) Cytoplasm and cell membrane divide.

Question 32

What is the result of mitosis?

Answer 32

Left with two daughter cells – identical to parent cell as same DNA.

Question 33

What process do prokaryotic cells use to reproduce?

Answer 33

Binary Fission.

Question 34

What are the 4 stages of binary fission?

Answer 34

1) Circular DNA strands and plasmids replicate.
2) Cell gets bigger, circular DNA strands go to opposite poles (ends).
3) Cytoplasm begins to divide and new cell walls form.
4) Cytoplasm divides and two daughter cells are produced.

Question 35

What happens to bacteria reproduction if the conditions are not favourable?

Answer 35

They stop replicating and die.

Question 36

What is mean division time?

Answer 36

The average time for a cell division to take place.

Question 37

How do you calculate the number of cells produced in a given time from the mean division time?

Answer 37

Work out the number of divisions that occur in the given time period.
Then, raise 2 to the power of the number of divisions.

Question 38

How many different types of cell can embryonic stem cells differentiate into?

Answer 38

Every type.

Question 39

How many different types of cell can stem cells from adult bone marrow turn into?

Answer 39

Only some types, mainly blood cells.