1.1

Question 1

Principles of the cell theory

Answer 1

1. All living things are composed of cells
2. The cell is the smallest unit of life
3. Cells only arise from pre-existing cells

Question 2

Caveats to cell theory

Answer 2

• striated muscle fibres
• Aseptate fungal hyphae
• giant algae

Question 3

7 functions integral to survival

Answer 3

Metabolism
Reproduction
Sensitivity
Homeostasis
Excretion
Nutrition
Growth

Question 4

Rate of a metabolism

Answer 4

Function of its mass/volume
Larger cells require more energy to sustain essentials functions

Question 5

As a cell grows ..

Answer 5

Volume increases faster than surface area
If metabolic rate exceeds rate of exchange of vital materials and waste, the cell will eventually divide. Therefore they tend to divide in order to remain small

Question 6

Increasing surface area to volume ratio

Answer 6

Cells and tissues that are special for gas and material exchanges will increase their surface area to optimise material transfer
I.e. villi and alveoli

Question 7

Magnification

Answer 7

Image = actual x magnification

Question 8

Prokaryotes

Answer 8

Lack nucleus
Either classified into archaebacteria (found in extreme environment) or eubacteria (traditional)

Question 9

Cytoplasm

Answer 9

P + E internal Fluid

Question 10

Nucleoid

Answer 10

P region of the cytoplasm where the dna is located
(DNA strand is circular and called genophore)

Question 11

Plasmids

Answer 11

P autonomous circular DNA molecules that may be transferred between bacteria

Question 12

Ribosomes

Answer 12

P + E complexes of RNA and protein that are responsible for polypeptide synthesis

Question 13

Cell membrane

Answer 13

P + E semi permeable membrane and selective barrier surrounding the cell

Question 14

Cell wall

Answer 14

P + E(p) rigid outer covering made of peptidoglycan, maintains shape and prevents bursting

Question 15

Slime capsule

Answer 15

P a thick polysaccharide layer used for protection against desiccation (drying out) and phagocytes

Question 16

Flagella

Answer 16

P long slender projections containing mortar protein that enables movement

Question 17

Pili

Answer 17

P hair like extensions that enable adherence to surfaces or mediate bacterial conjugation

Question 18

Binary fission

Answer 18

Circular dna is copied in response to a replication symbol
The two dna loops attach to the membrane
The membrane elongates and pinches off (cytokenisis) forming two cells

Question 19

Eukaryotes

Answer 19

4 distinct kingdoms
Protista (without specialised tissue)
Fungi
Plantae
Animalia

Question 20

Cytoskeleton

Answer 20

P + E a filamentous scaffolding within the cytoplasm, provides internal stricter and mediates intercellular transport

Question 21

Plasma membrane

Answer 21

Phospholipid bilayer embedded with proteins

Question 22

Nucleus

Answer 22

E double membrane structure with pores; contains an inner region called nucleolus. Stores genetic material as chromatin, site of ribosome assembly

Question 23

Endoplasmic reticulum

Answer 23

E A membrane network that transports materials between organelles. (Smooth ER = lipids ; rough ER = proteins)

Question 24

Golgi apparatus

Answer 24

E an assembly of vesicles and folded membranes that sorts, stores, modifies and exports secretory products

Question 25

Mitochondrion

Answer 25

E Site of aerobic respiration

Question 26

Peroxisome

Answer 26

E Catalyses breakdown of toxic substances

Question 27

Centrosome

Answer 27

Radiating microtubules form spindle fibres and contribute to cell division

Question 28

Chloroplast

Answer 28

Pl site of photosynthesis

Question 29

Vacuole

Answer 29

Pl maintain hydrostatic pressure

Question 30

Lysosome

Answer 30

Membranous sacs filled with hydrolytischem enzymes. Breaks down macromolecules

Question 31

Electron microscopy

Answer 31

Use electron beams focused by electromagnets to magnify and resolve microscopic specimen

Question 32

Phospholipid bilayer

Answer 32

Polar head (hydrophilic) composed of glycerol and a phosphate molecule Consists of two non-polar tails (hydrophobic) composed of fatty acid chains Amphipathic

Question 33

Arrangement in membranes

Answer 33

Phospholipids spontaneously arrange into a Bilayer Hydrophobic tails phase inwards ad are shielded from surrounding polar fluids

Question 34

Properties of phospholipid bilayer

Answer 34

Held together by weak hydrophobic interactions between tails Layers restrict passage of many substances Individual phospholipids can move within bilayer, allowing for fluidity and flexibility Fluidity allows for spontaneous breaking and reforming of membranes