2.3

Question 1

What does the “ultrastructure of a cell” mean? (1)

Answer 1

(1) each cell type has an INTERNAL STRUCTURE that suits it for its job

Question 2

What are the functions of the nucleus? (5)

Answer 2

(1) manufactures ribosomal RNA & ribosomes
(2) control centre of the cell
(3) produces mRNA & tRNA
(4) controls protein synthesis
(5) retains the genetic material of the cell

Question 3

What is the structure of the nucleus. Explain what each one does. (5+4)

Answer 3

(1) NUCLEAR ENVELOPE —> (6) controls entry & exit of materials + contains reactions taking place
(2) NUCLEAR PORES —> (7) allows large molecules to pass through (RNA)
(3) NUCLEOPLASM —> (8) glandular, jelly-like material in nucleus
(4) CHROMOSOMES
(5) NUCLEOLUS —> (9) small sphere in the nucleoplasm that manufactures ribosomes and ribosomes RNA

Question 4

What are the functions of the mitochondria? (2)

Answer 4

(1) produces ATP
(2) undergoes aerobic respiration

Question 5

What is the structure of the mitochondria? Explain what each part does. (3+3)

Answer 5

(1) DOUBLE MEMBRANE —> (4) controls entry & exit of materials
(2) CRISTAE —> (5) (foldings of the inner membrane) provides large SA for attachment of enzymes & respiration
(3) MATRIX —> (6) (contains enzymes) allows the control of the production of its own enzymes

Question 6

What is the structure of the chloroplast? Explain what each part does. (3+3)

Answer 6

(1) CHLOROPLAST ENVELOPE —> (4) (double plasma membrane) controls what enters & leaves the cell
(2) STROMA —> (5) (fluid filled matrix) 2nd stage of photosynthesis occurs
(3) GRANA —> (6) (contains THYLAKOIDS, which contains chlorophyll) 1st stage of photosynthesis occurs + large SA for attachment of enzymes

Question 7

What is the COMMON structure of the rER and sER? (2)

Answer 7

(1) continuous with the OUTER MEMBRANE of the NUCLEUS
(2) enclosed a network of tubules & CISTERNAE (flattened sacs)

Question 8

What are the functions & structure of the rER? (2+1)

Answer 8

F:
(1) provides LARGE SA for PROTEIN & GLYCOPROTEIN SYNTHESIS
(2) provides a pathway for the transport of materials throughout the cell.

S:
(1) RIBOSOMES present on outer surface

Question 9

What are the functions & structure of the sER? (2+2)

Answer 9

F:
(1) synthesise, store & transport LIPIDS
(2) synthesise, store & transport CARBOHYDRATES

S:
(1) LACKS RIBOSOMES on its surface
(2) more tubular in appearance

Question 10

If a cell produces large quantities of carbs, proteins & lipids, what does that indicate about the cell’s ER? (1)

Answer 10

It’s very large / extensive

Question 11

What are the functions of the golgi apparatus? (5)

Answer 11

(1) produces LYSOSOMES
(2) transports, modifies, & stores lipids
(3) produces GLYCOPROTEINS
(4) produces SECRETORY ENZYMES
(5) synthesise & transport CARBS

Question 12

What’s the structure of the golgi apparatus? Describe each. (4)

Answer 12

(1) CISTERNAE —> (3) stack of membranes that make up flattened sacs
(2) VESICLES —> (4) small, rounded & hollow structures

Question 13

Describe the process of transporting proteins & lipids through the golgi apparatus. (5)

Answer 13

(1) proteins & lipids from the ER are passed through the golgi
(2) it modifies these proteins by adding non-protein components to them (e.g. carbs)
(3) it “LABELS” them so they’ll be accurately sorted & sent to the correct destination
(4) they’re transported via VESICLES (which are pinched off from the ends of the cisternae)
(5) the vesicles may move to the cell surface where they fuse w the cell membrane & release their contents to outside

Question 14

In which type of cells are the golgi apparatus well developed in? (1)

Answer 14

Epithelial cells that line the intestines

Question 15

What are the functions of lysosomes? (4)

Answer 15

(1) hydrolyses material ingested by phagocytic cells
(2) release enzymes to outside the cell (EXOCYTOSIS)
(3) digest worn-out organelles
(4) completely break down cells after they have died (AUTOLYSIS)

Question 16

What is the structure of lysosomes? (2)

Answer 16

(1) CONTAIN LYSOZYMES (hydrolyses bacterias cell wall)
(2) they’re small spheres

Question 17

In which type of cells are lysosomes abundant in? (1)

Answer 17

(1) epithelial / secretory

Question 18

What is the structure of ribosomes? (3)

Answer 18

(1) small, cytoplasmic granules
(2) HAS 2 SUBUNITS: 1 large & 1 small, (3) each contain ribosomal RNA & proteins

Question 19

What are the 2 types of ribosomes? Where do they occur? What sizes are they? (6)

Answer 19

(1) 70S: (2) prokaryotic cells
(3) <25 nm
(1) 80S: (2) eukaryotic cells
(3) 25 nm

Question 20

What are the functions of cell wall? (2)

Answer 20

(1) provides mechanical strength in cells (withstands osmotic changes) & plants
(2) allows water to pass through it

Question 21

What’s the structure of the cell wall? (4)

Answer 21

(1) consists of microbfibrils of cellulose embedded in a matrix (plant cells)
(2) MIDDLE LAMELLA —> (4) thin layer that marks the boundary between other cells’ cell walls
(3) in FUNGI, cell wall can be made from either CHITIN, GLYCAN, or GLYCOPROTEINS

Question 22

What are the functions of the vacuole? (3)

Answer 22

(1) supports herbaceous plants by making them TURGID
(2) has SUGARS & AMINO ACIDS as temporary food stores
(3) has PIGMENTS that colour flower petals

Question 23

What is the structure of the vacuole? (3)

Answer 23

(1) fluid-filled sac
(2) bound by a single membrane (TONOPLAST)
(3) contains a solution of mineral salts, sugars, amino acids, pigments, wastes, etc.

Question 24

How can you deduce the role of a cell by looking at its ultrastructure? (1)

Answer 24

By looking at the NUMBER & SIZE of the organelles it contains