Unit 1

Question 1

Archaebacteria

Answer 1

Unicellular, prokaryotes, both autotrophs and heterotrophs

Question 2

Eubacteria

Answer 2

Unicellular, prokaryotes, both autotrophs and heterotrophs

Question 3

Protists

Answer 3

Most unicellular, eukaryotes, both autotrophs and heterotrophs

Question 4

Fungi

Answer 4

Most multicellular, eukaryotes, heterotrophs

Question 5

Plants

Answer 5

Multicellular, eukaryotes, autotrophs

Question 6

Animals

Answer 6

Multicellular, eukaryotes, heterotrophs

Question 7

Characteristics of living things

Answer 7

Metabolism, reproduction, sensitivity, homeostasis, excretion, nutrition, growth

Question 8

3 axioms of cell theory

Answer 8

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

Question 9

Exceptions to cell theory

Answer 9

1. Striated muscle (has hundreds of nuclei)
2. Aseptate fungi (many nuclei)
3. Giant algae (huge)

Question 10

Advantages and disadvantages of asexual reproduction

Answer 10

Advantages: faster, more efficient, higher mutation rate, no need for a mate
Disadvantages: little to no genetic variation

Question 11

Advantages of being multicellular

Answer 11

Emergent properties: functions that arise from the interaction of individual components (organ systems, etc.)

Question 12

Key characteristics of stem cells

Answer 12

1. Self-renewal, rapid rate of mitosis

2. Potency, ability to differentiate

Question 13

Types of stem cells

Answer 13

Totipotent: can become any cell in body plus extra-embryonic cells
Pluripotent: can become any cell in body
Multipotent: can become different types of cells, but not any
Unipotent: cannot differentiate but capable of self renewal

Question 14

2 models of cell membrane

Answer 14

Davson-Danielli: sandwich with protein layers surrounding phospholipids. Believed because electron micrographs showed 3 layers, 2 dark lines believed to be proteins with middle light layer being phospholipids

Singer and Nicholson: fluid mosaic, proteins imbedded in the phospholipid bilayer and free to move with the phospholipids

Question 15

Shortcomings of sandwich model

Answer 15

1. Assumed that all membranes are the same, yet different functions are performed
2. Proteins are largely hydrophobic, unlikely for them to be the outer layers

Question 16

Proofs for fluid mosaic model

Answer 16

1. Freeze-etched electron micrographs: rapidly frozen and cleaved to split bilayer. Rough, with bumps being proteins
2. Structure of membrane proteins: proteins extracted and analyzed, different sizes and globular, unlike the type to form continuous layers
3. Fluorescent antibody tagging: red/green markers attached to antibodies that bind to proteins, colours were mixed showing fluidity

Question 17

Name for hydrophobic/philic behaviour of phospholipids

Answer 17

Amphipathic

Question 18

Role of cholesterol in membrane

Answer 18

Maintains fluidity. When warm, acts as speed bump. When cold, keeps them apart

Question 19

Alternate method of maintaining fluidity

Answer 19

Kinds/bends in hydrocarbon tails with double bonds

Question 20

Factors affecting diffusion rate

Answer 20

Concentration gradient (steeper = faster)
Size (smaller = faster)
Temperature (hotter = faster)

Question 21

Particles that can diffuse

Answer 21

Small uncharged polar molecules (water, glycerol, ethanol) and small hydrophobic molecules (oxygen, carbon dioxide)

Question 22

Particles that cannot diffuse

Answer 22

Ions, large uncharged polar molecules (amino acids)

Question 23

2 types of proteins used in facilitated diffusion

Answer 23

Channel proteins, carrier proteins

Question 24

2 types of active transport

Answer 24

Direct hydrolysis of ATP, indirectly coupling transport (e.g. proton pump, hydrogen ions, glucose)

Question 25

Types of bulk transport

Answer 25

Endocytosis: pinocytosis (extracellular fluid sipped into vesicles and molecules taken up), phagocytosis (particle in vacuole is engulfed, fuses with lysosome for digestion), receptor mediated (when specific receptors are full, membrane pinches closed) Exocytosis

Question 26

Accumulation and degradation of mitotic cyclins

Answer 26

Accumulate during G2 -> MPF formed -> cell signalled to enter mitosis Degrade -> MPF inactivated -> cell exits mitosis and divides

Question 27

MPF activation

Answer 27

Cyclins accumulate, CDKinase adds a phosphate to the promoting factor, factor activated

Question 28

What controls cyclin levels

Answer 28

Cell size, completion of DNA replication, cellular environment

Question 29

Oncogenes

Answer 29

Gas pedal. In normal state, codes for proteins that control the cell cycle. When mutated the proteins exhibit increased activity that contributes to tumor growth

Question 30

Tumor suppressor genes

Answer 30

Absence of brakes. Produce proteins that regulate cell division. When mutated, unable to do this

Question 31

How living things can be formed

Answer 31

1. Building blocks need to be formed, simple organic molecules synthesized 2. Simple molecules must assemble to form more complex polymers 3. Polymers must have the ability to self-replicate 4. Polymers are separated from the external environment, form protobionts with an internal chemistry different from the surroundings

Question 32

Evidence for endosymbiosis

Answer 32

Double membranes Own set of DNA Similar in size to bacteria