Topic 3

Question 1

What are the common features in the cells of all living organisms?

Answer 1

Membranes, cytoplasm, ribosomes, some form genetic material

Question 2

What are the types of cell?

Answer 2

Prokaryotic cells and eukaryotic cells

Question 3

Which is more complex: prokaryotic or eukaryotic cells?

Answer 3

Eukaryotic- also bigger than prokaryotic cells

Question 4

Where are prokaryotic cells found?

Answer 4

In simple organisms like bacteria

Question 5

Where are eukaryotic cells found?

Answer 5

In all types of plants and animals

Question 6

List the organelles found in prokaryotic cells

Answer 6

Cell wall, Capsule, Plasmid, Flagellum, Pili, Ribsomes, Mesosomes, Circular DNA

Question 7

Function of cell wall

Answer 7

Supports the cell and stops it changing shape

Question 8

Function of capsule

Answer 8

Helps to protect bacteria from attacks by immune system

Question 9

Function of flagellum

Answer 9

Long hair-like structure that helps to move the cell

Question 10

Function of pili

Answer 10

It’s used in the transfer of genetic material by helping stick prokaryotes stick together

Question 11

Function of mesosomes

Answer 11

Inward folds in the plasma membranes with an unknown function

Question 12

What’s the difference between the normal circular DNA and plasmids in bacteria?

Answer 12

Plasmids are smaller loops of DNA that can be passed between cells

Question 13

List the organelles in eukaryotic cells

Answer 13

Nucleus, nucleolus, rough ER, smooth ER, mitochondria, centrioles, lysosomes, Golgi apparatus

Question 14

Function of nucleus and nucleolus

Answer 14

Ribosomes and RNA are made in the nucleolus. The nucleus controls the cell’s activities because DNA is located here

Question 15

Function of rough ER

Answer 15

Folds and processes proteins

Question 16

Function of smooth ER

Answer 16

Synthesises and processes lipids

Question 17

Function of ribosomes in prokaryotic and eukaryotic cells

Answer 17

Site of protein synthesis

Question 18

Function of mitochondria

Answer 18

Site of later stages of aerobic respiration

Question 19

Function of centrioles

Answer 19

The separation of chromosomes in cell division

Question 20

Function of lysosomes

Answer 20

Ingestion of invading cells and break down of unwanted structures, both by digestive enzymes

Question 21

Function of Golgi apparatus

Answer 21

Modifies proteins and packages them in vesicles for transport

Question 22

How are proteins transported out of the cell?

Answer 22

• They enter the rER, assuming a 3D shape as they make their way through
• Vesicles containing the protein fuse to form flattened sacs of the Golgi apparatus
• Proteins are modified within the Golgi apparatus
• Vesicles with the modified protein pinch of the Golgi apparatus and fuse with the cell membrane, releasing it

Question 23

How do sperm fertilise eggs?

Answer 23

1) Sperm reach the ovum
2) Chemicals are released from cells surrounding the ovum, triggering acrosome reaction
3) The acrosome swells, fusing with the sperm cell membrane
4) Digestive enzymes are released from acrosome
5) Sperm fuses with ovum membrane and enters
6) Enzymes released from ovum thicken zona pellucida stop any more sperm entering
7) The two nuclei fuse

Question 24

Why is mitosis needed?

Answer 24

For growth of multi-cellular organisms, repairing damaged tissues, asexual reproduction

Question 25

What are the stages of the cell cycle?

Answer 25

Growth phase 1- cell grows, new organelles and proteins are made Synthesis- DNA replicates to prepare for mitosis Growth phase 2- proteins for cell division made Mitosis- cell cycle begins and ends here

Question 26

What are the five stages of mitosis?

Answer 26

Prophase, metaphase, anaphase, telophase, cytokenesis

Question 27

Describe how proteins are modified, packaged and secreted by the cell (4 marks)

Answer 27

1. In the rER proteins are folded- forms 3-D shape 2. The proteins is packaged into transport vesicles by the rER 3. The vesicles move to the Golgi apparatus and fuse with it 4. They are then changed in Golgi apparatus ; 5. The protein is transferred in secretory vesicles from the Golgi apparatus to the cell membrane 6. Vesicles fuse with cell surface membrane- protein is secreted

Question 28

Describe what happens during prophase

Answer 28

Chromosomes condense to become shorter and fatter. Centrioles start moving to opposite sides of the cell, forming networks of spindle. The nuclear envelope breaks down

Question 29

Describe what happens during metaphase

Answer 29

Chromosomes line up along the middle of the cell. They then become attached to the spindle by their centromere.

Question 30

Describe what happens during anaphase

Answer 30

Centromeres divide, separating each pair of sister chromatids. Spindles contract, pulling chromatids to opposite poles of the cell.

Question 31

Describe what happens during telophase

Answer 31

The chromatids reach opposite poles of the cell and uncoil. They are called chromosomes again. A nuclear envelope forms around the chromosomes, making two nuclei,

Question 32

Describe what happens during cytokenesis

Answer 32

The cytoplasm divides to form two daughter cells that are genetically identical to each other and to the parent cell.

Question 33

Describe the process of meisosis

Answer 33

1) DNA replicates to form two identical copies of each chromosome, called chromatids 2) The chromosomes pair up to form homologous pairs 3) The first division results in the separation of homologous pairs 4) The second division results in the pairs of chromatids being seperated 5) 4 genetically different gametes are produced.