Unit 1

Question 1

Negative feedback loop

Answer 1

4 components:
1. Stimulus
- cold
2. Sensors
- receptors for temp
3. Effector
- muscles
4. Response
- heat production

Question 2

Conformers vs regulators

Answer 2

2 categories of organisms when responding to environmental change
1. Conformers
- do not maintain homeostasis
- line of conformity
2. Regulators
- maintain homeostasis
- zone of stability

Question 3

Environmental change proceeds at different rates and evokes different responses

Answer 3

1. Minutes to hours
   - I.e. exercise, temp, etc.
   - change: physiological adjustment (instantaneous and easily reversed)
2. Weeks to months
   - I.e. altitude, day length, etc.
   - change: acclimatization (slower, over many days, reversible)
3. Geologic time
   - I.e. new habitats, climate change
   - change: evolutionary change (selection of new traits, non-reversible)

Question 4

Cell membranes

Answer 4

• 2 phospholipid bilayers
  — polar head groups (hydrophilic) and non polar tails (hydrophobic)
  — phospholipids are able to move within membarane
• arrange themselves spontaneously
• composed of lipids, proteins, and carbs

Question 5

Saturated fatty acid chains

Answer 5

• lack double bond chains
• straight structure allows tight packing

Question 6

Unsaturated fatty acid chains

Answer 6

• one or more double bonds
• kinks reduce tightness of packing
  —cold water species have more double bonds to maintain fluid membranes

Question 7

Plasma membrane selective barriers

Answer 7

• selective permeability is key to maintain homeostasis SO:
• some items move freely or under certain conditions
  — gases, lipids, small polar molecules
• other move not at all
  — large macromolecules
  — hydrophobic prevents ion movement

Question 8

Passive transport

Answer 8

• simple diffusion
  -movement into and out of cells
• from higher to lower concentration gradient through permeable membrane
  —when equal no net movement but random motion continues in both directions

Question 9

Osmosis

Answer 9

• water movement
  — from higher solute conc and low water conc -> low solute conc and high water conc
  — membrane allows water movement but not solute

Question 10

Aquaporins

Answer 10

• proteins that allow water to move quickly across cell membranes
  — help concentrate and dilute ursine in the kidneys

Question 11

Active transport

Answer 11

• facilitated diffusion
• channel and carrier proteins
• allows movement against Concentration gradient
  —. I.e nutrients or waste

Question 12

Primary active transport

Answer 12

• uses ATP directly
  — ex. Sodium-potassium pump
  ——3 sodium ions pumped out, 2 potassium ions pumped in

Question 13

Antiporter vs symporter

Answer 13

Antiporter
- ions moving in opposite directions
Symporter (co-transporter)
- ions moving in same direction

Question 14

Secondary active transport

Answer 14

• uses ATP indirectly
  —protons pumped across by primary transport
  — creating electrochemical gradient
  — Antiporter uses gradient to move different molecules out of cell (against gradient)