1.2 Cells as the basic units of living organisms

Question 1

structure of cell surface membrane

Answer 1

• phospholipid bilayer
• diameter around 10nm

Question 2

function of cell surface membrane

Answer 2

• separate cell contents from surrounding environment
• control passage of substances into and out of cells

Question 3

structure of nucleus

Answer 3

• separated from cytoplasm by double membrane
• nuclear envelope contains many pores
• nucleolus

Question 4

function of nucleus

Answer 4

contains DNA arranged into chromosomes

Question 5

function of nuclear envelope

Answer 5

• contain nuclear pores
• important channels for allowing mRNA and ribosomes to travel out of nucleus
• allow enzymes and signalling molecules to move in

Question 6

function of nucleolus

Answer 6

site of ribosome production

Question 7

structure of rough endoplasmic reticulum

Answer 7

• continuous folds of membrane
• linked with nuclear envelope
• covered in ribosomes

Question 8

function of rough endoplasmic reticulum

Answer 8

process proteins that are produced on ribosomes

Question 9

function of smooth endoplasmic reticulum

Answer 9

• involved in production of lipids
• steroid hormones (eg oestrogen and testosterone)

Question 10

structure of golgi body

Answer 10

• series of flattened sacks of membrane
• not connected to other membrane-bound compartments

Question 11

function of golgi body

Answer 11

modify proteins and package them into vesicles

Question 12

structure of mitochondria

Answer 12

• surrounded by double-membrane
• inner membrane folded to form cristae
• mitochondrial matrix contains enzymes needed for aerobic respiration
• small circular pieces of DNA (mitochondrial DNA) and ribosomes also found in matrix

Question 13

function of mitochondria

Answer 13

• site of aerobic respiration within eukaryotic cells
• mitochondrial DNA and ribosomes allow production of proteins required for respiration

Question 14

structure of ribosomes

Answer 14

• found in cytoplasm of all cells or part of RER
• complex of ribosomal RNA (rRNA) and proteins

Question 15

function of ribosomes

Answer 15

site of translation during protein

Question 16

what ribosomes are found in eukaryotic cells

Answer 16

80S ribosomes
- composed of 60S and 40S subunits

Question 17

what ribosomes are found in prokaryotes

Answer 17

70S ribosomes
- 50S and 30S subunits

Question 18

structure of vesicles

Answer 18

• small, membrane-bound sacs
• can be pinched off ends of golgi body (golgi vesicles)

Question 19

function of vesicles

Answer 19

• used by cells for transport and storage
• can fuse with cell surface membrane to allow exocytosis
• can bud from membrane during endocytosis

Question 20

structure of lysosomes

Answer 20

• specialised vesicles
• containing hydrolytic enzymes

Question 21

function of lysosomes

Answer 21

hydrolytic enzymes break down biological molecules eg
- waste materials (eg worn out organelles)
- engulfed pathogens during phagocytosis
- cell debris during apoptosis

Question 22

what is apoptosis

Answer 22

programmed cell death

Question 23

structure of centrioles

Answer 23

• hollow fibres made of microtubules
• perpendicular centrioles form centrosome

Question 24

are centrioles found in flowering plants and fungi

Answer 24

no

Question 25

function of centrosome

Answer 25

organises spindle fibres during cell division

Question 26

structure of microtubules

Answer 26

- hollow tubes made of tubilin protein - α and β tubulin proteins combine to form dimers - dimers joined into protofilaments - 13 protofilaments in cylinder make microtubule

Question 27

function of microtubules

Answer 27

- make up cytoskeleton of cell - provide support and movement of cell

Question 28

structure of cilia

Answer 28

- hair-like projections made from microtubules - found on surface of some cells

Question 29

function of cilia

Answer 29

allow movement of substances over cell surface

Question 30

structure of microvilli

Answer 30

cell membrane projections

Question 31

function of microvilli

Answer 31

increase surface area for absorption

Question 32

structure of cell wall

Answer 32

- outside cell surface membranes - freely permeable

Question 33

function of cell wall

Answer 33

offer structural support, provided by: - polysaccharide cellulose in plants - chitin in fungi

Question 34

structure of chloroplasts

Answer 34

- surrounded by double-membrane - thylakoids stack tg to form grana - grana joined by lamellae - chlorophyll found in membranes of thylakoids - small circular pieces of DNA and ribosomes

Question 35

function of chloroplasts

Answer 35

- chlorophyll absorbs light energy for photosynthesis - DNA and ribosomes synthesise proteins needed in chloroplast replication and photosynthesis

Question 36

structure of plasmodesmata

Answer 36

bridges of cytoplasm between neighbouring plant cells

Question 37

function of plasmodesmata

Answer 37

allow transfer of substances between plant cells

Question 38

structure of large permanent vacuole

Answer 38

- surrounded by tonoplast (partially permeable membrane)

Question 39

function of large permanent vacuole

Answer 39

- store cell sap - provide additional structural support to cells

Question 40

animal and plant cell common structures

Answer 40

(9) - cell surface membrane - cytoplasm - nucleus - mitochondria - rough/smooth endoplasmic reticulum - golgi bodies - vesicles and lysosomes - ribosomes - microtubules

Question 41

structures unique to plant cells

Answer 41

(4) - cellulose cell wall - large permanent vacuoles - chloroplasts - plasmodesmata

Question 42

structures unique to animal cells

Answer 42

- centrioles - microvilli

Question 43

what do cells use ATP for

Answer 43

from respiration for energy requiring processes

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