C2

Question 1

Define eukaryotic cell

Answer 1

A type of cell that contains a true nucleus along with membrane-bound organelles.

Question 2

Describe the structure of the nucleus

Answer 2

• Surrounded by nuclear envelope which is semi-permeable and double membraned
• Nuclear pores allow substances to enter/exit
• Dense nucleolus (made of RNA and proteins) assembles ribosomes

Question 3

Describe the function of the nucleus

Answer 3

• Contains DNA coiled around chromatin into chromosomes
• Coordinates cellular activities

Question 4

What is chromatin?

Answer 4

A DNA-protein complex found in eukaryotic cells.

Question 5

Describe the structure of mitochondria

Answer 5

• Surrounded by double membrane, mitochondrial envelope
• Folded inner membrane forms cristae (large surface area)
• Fluid matrix contains mitochondrial DNA, respiratory enzymes, lipids and proteins

Question 6

Describe the function of mitochondria

Answer 6

Site of aerobic respiration to produce ATP.

Question 7

Describe the structure of the endoplasmic reticulum (ER)

Answer 7

Series of flattened membrane-bound sacs (cisternae) within the cytoplasm, continuous with the nuclear envelope
Two types: rough ER and smooth ER

Question 8

Describe the function of the smooth endoplasmic reticulum (SER)

Answer 8

Lipid synthesis

Question 9

Describe the function of the rough endoplasmic reticulum (RER)

Answer 9

Many ribosomes attached for protein synthesis and transport.

Question 10

Describe the structure of ribosomes

Answer 10

• Made from rRNA and proteins
• Found free in the cytoplasm or associated with the RER

Question 11

Describe the function of ribosomes

Answer 11

• Site of protein synthesis (translation)
• Large subunit joins amino acids
• Small subunit reads RNA

Question 12

Describe the structure of the Golgi body

Answer 12

Planar stack of membrane-bound, flattened sacs
Cis face aligns with RER
Molecules are processed in cisternae
Vesicles bud off trans face via exocytosis

Question 13

Describe the function of the Golgi body

Answer 13

Modifies and packages proteins for export
Synthesises glycoproteins

Question 14

Describe the structure and function of lysosomes

Answer 14

Fluid-filled vesicles surrounded by a single membrane, contain enzymes
Role in phagocytosis, digest unwanted materials in the cytoplasm

Question 15

Describe the structure of centrioles

Answer 15

Cylindrical structure
Organised into microtubules in a 9+0 pattern
Found in pairs in centrosomes

Question 16

Describe the function of centrioles

Answer 16

Migrate to opposite poles of the cell during prophase
Involved in the organisation of spindle fibres

Question 17

Describe the structure of a chloroplast

Answer 17

Disk shaped surrounded by double membrane
Thylakoids - flattened discs stacked to form grana
Grana - contain photosystems with chlorophyll
Intergranal lamellae - tubes attach thylakoids in adjacent grana
Stroma - fluid-filled matrix

Question 18

What is the function of a chloroplast?

Answer 18

Site of photosynthesis

Question 19

Describe the structure of the permanent vacuole in plants

Answer 19

Surrounded by a single membrane, tonoplast
Contains cell sap (mineral ions, water, enzymes, soluble pigments)

Question 20

Describe the function of the permanent vacuole in plants

Answer 20

Controls turgor pressure
Water storage
Isolates harmful waste products
Maintains pH

Question 21

Define plasmodesmata

Answer 21

Microscopic channels between plant cell walls that facilitate communication and symplastic transport.

Question 22

Define prokaryotic cell

Answer 22

A type of cell that does not contain any membrane-bound organelles or a true nucleus.

Question 23

Describe the structure and function of the flagella in prokaryotic cells

Answer 23

Long, whip-like protrusion made of flagellin
Rotates to propel the organism
Sensory organ

Question 24

How is genetic information stored in prokaryotes?

Answer 24

Plasmids - small rings of DNA that carry non-essential genes, exchanged between bacterial cells via conjugation
Loop of DNA - circular DNA stored in the nucleoid region of the cell

Question 25

Describe the structure and function of pili in prokaryotic cells

Answer 25

Hair-like microfibers made of pilin that extend through the cell wall Enable the attachment of bacteria to each other and to other surfaces

Question 26

Describe the structure and function of the mesosome

Answer 26

Infolds of the cell membrane Increase the surface area of the cell, aiding cellular respiration

Question 27

What is the function of the capsule in prokaryotic cells?

Answer 27

Protective, slimy layer Helps the cell to retain moisture and adhere to other surfaces

Question 28

Which organelles are found in both eukaryotic and prokaryotic cells?

Answer 28

Cell membrane Cytoplasm with a form of cytoskeleton (although cytoskeleton of eukaryotes is more significant) Ribosomes

Question 29

Contrast eukaryotic and prokaryotic cells

Answer 29

* Prokaryotic: Small, unicellular; No membrane-bound organelles, no nucleus; Circular DNA, not associated with proteins; 70S ribosomes; Reproduce via binary fission; Peptidoglycan cell wall * Eukaryotic: Large, often multicellular; Contain membrane-bound organelles and true nucleus; Linear chromosomes associated with histones; 80S ribosomes; Reproduce via sexual or asexual reproduction; Cell wall made of cellulose (plants) or chitin (fungi)

Question 30

Contrast eukaryotic plant and animal cells

Answer 30

* Plant cells: Cellulose cell wall; Large permanent vacuole; Contain chloroplasts; No pseudopodia * Animal cells: No cell wall; Small temporary vacuoles (vesicles); No chloroplasts; Some may have pseudopodia

Question 31

Describe cell theory

Answer 31

The cell is the fundamental unit of all life forms New cells can be formed from existing cells Cells contain genetic material which can be transferred to daughter cells

Question 32

What is a virus?

Answer 32

A non-living microorganism that consists of genetic material surrounded by a protein husk.

Question 33

How do viruses differ from prokaryotic and eukaryotic cells?

Answer 33

* Virus: Non-living; Smaller and simpler in structure; Genetic material in the form of DNA or RNA; Can only reproduce within a host cell; No ribosomes * Prokaryotic and eukaryotic cells: Living; Larger and more complex structure; Genetic material in the form of DNA; Independent cell division, sexual or asexual; Contain ribosomes

Question 34

How are multicellular organisms organised?

Answer 34

Many cells make up a tissue Many tissues make up an organ Many organs make up an organ system

Question 35

Define tissue

Answer 35

A group of cells working together to carry out a specific function.

Question 36

Define organ

Answer 36

A group of tissues working together to carry out a specific function.

Question 37

Define organ system

Answer 37

A group of organs working together to carry out a specific function.