Biology Unit 1

Question 1

What is the difference between unsaturated/saturated compounds?

Answer 1

unsaturated: compound w/multiple carbon-carbon bonds
saturated: compound w/one carbon-carbon bond. Can’t combine with other atoms

Question 2

What is the difference between competitive/non-competitive inhibition?

Answer 2

Competitive: poison that competes with substrate molecule for active site
non-competitive: poison blocks active site permanently

Question 3

What is the active site?

Answer 3

Portion of enzyme in contact with substrate

Question 4

What is abiogenesis?

Answer 4

Formation of living organisms from non-living matter

Question 5

What are the differences between prokaryotes and eukaryotes?

Answer 5

Prokaryote: no nucleus or membrane bound organelles, unicellular, circular DNA

Eukaryote: nucleus, membrane bound organelles, multicellular, linear DNA

Question 6

What is the endosymbiotic hypothesis?

Answer 6

Small groups of prokaryotic cells become permanently integrated. Small cells live inside large cells, which forms eukaryotes

Question 7

What is the structure and function of the nucleus

Answer 7

controls cell division 
surrounded by double membrane (nuclear envelope, selectively permeable)
contains nucleolus (proteins, DNA, RNA) which makes ribosomes

Question 8

What is the structure and function of the endoplasmic reticulum

Answer 8

Network of flattened sacs (cisternae)
Smooth: synthesis and transport of lipids and steroids
Rough: ribosomes synthesis proteins, cisternae transport proteins

Question 9

What is the structure and function of the Mitochondria

Answer 9

double membrane, inner membrane folded into cristae
site of chemical reactions
Has independent DNA and ribosomes to make enzymes, self-replicate

Question 10

What is the structure and function of the Golgi Body

Answer 10

Made of Cisternae sacks

receive enzymes, proteins, made in ER and encloses them in membranes before releasing in cytoplasm or outside cells

Question 11

What is the structure and function of the Vesicle

Answer 11

Sac, transports molecules around cell

Question 12

What is the structure and function of the Lysosome

Answer 12

has digestive enzymes
cellular products and wastes broken down by lysosomes (autophagy)
can break down cell completely (autolysis)

Question 13

What is the structure and function of the Centrioles

Answer 13

2 cylindrical bodies next to nucleus

organise DNA during mitosis, move cells by flagella or cilia

Question 14

What is the structure and function of the Cell Wall

Answer 14

Cellulose Wall encloses cell membrane, thickened with lignin
Mechanical support and protection
Cell Wall has gaps with plasmodesmata

Question 15

Plastids (chloroplasts, chromoplasts)

Answer 15

Double Membraned
Chromoplasts: provide colour to leaves (non-photosynthetic)
Chloroplasts: has stroma and stacks of discs (grana). Each disk a thylakoid. Can self-replicate

Question 16

Vacuole

Answer 16

contains cell sap, storage, controls water levels

Question 17

Describe the Cell Membrane

Answer 17

Selectively-permeable barrier, provides mechanical support and is a receptor for chemical materials

Question 18

Describe the structure of the Cell Membrane

Answer 18

Phospholipid bilayer (hydrophilic head, hydrophobic tail)
Polarity restricts movement to only horizontal movement
protein channels allow passage of large/water soluble molecules

Question 19

What is the Fluid Mosaic Model

Answer 19

Molecules in cell membrane move freely, whilst some are fixed in position

Question 20

What is diffusion

Answer 20

molecules spread from higher concentration to lower concentration

Question 21

What are the 3 types of passive transport

Answer 21

1. Simple Diffusion
2. Facilitated Diffusion
3. Osmosis

Question 22

What is Simple Diffusion

Answer 22

unaided movement of molecules or ions through cell membrane

Question 23

What is Facilitated Diffusion

Answer 23

aided movement through molecules

Question 24

What is osmosis

Answer 24

movement of water molecules across cell membrane

Question 25

What is osmotic potential

Answer 25

capacity of solution to lose water molecules

Question 26

Describe a hypertonic surrounding

Answer 26

solute concentration in extracellular fluid is higher than in cytoplasm (low osmotic potential). Fluid moves out of cytoplasm

Question 27

Describe a hypotonic surrounding

Answer 27

solute concentration in extracellular fluid is lower than in cytoplasm (high osmotic potential). Fluid moves in the cytoplasm

Question 28

Describe an isotonic surrounding

Answer 28

Solute concentration is equal

Question 29

Describe the relationship between plasmolysis and turgor pressure

Answer 29

Plasmolysis is the shrinkage of the cytoplasm of a plant cell due to water loss by osmosis. To prevent this, turgor pressure (inward pressure by cell wall) is exerted.

Question 30

Define Active Transport

Answer 30

Transport of molecules across a membrane against the concentration gradient (needs ATP)

Question 31

Define Exocytosis

Answer 31

Active transport out of cells

Question 32

Define Endocytosis

Answer 32

Active transport into the cell