quiz 1

Question 1

Phylogenetic approaches to determine relatedness include

Answer 1

1. Genetic
2. Anatomy
3. Fossil records

Question 2

How do homologous and analogous structures differ?

Answer 2

Homologous: different function but shared embryonic origin

Analogous: similar function but different embryonic origin

Question 3

What is the difference between a positive and negative feedback loop? Which is more common?

Answer 3

With positive feedback, the response of the effectors amplifies the original stimulus. Whereas, with negative feedback, the response of the effectors reduces/removes the original stimulus.

Negative feedback is more common in the body.

Question 4

Why is it so important that our cells are small?

Answer 4

Our cells are small so that we have large surface area to volume ratio

Greater surface area is able to provide the inner volume with adequate nutrients and can sufficiently remove wastes. If a cell gets too big the door (surface area/cell membrane) won’t be big enough to support the volume of the cell.

Question 5

• Proteins from food are broken down into their smaller components, amino acids (Cata or Ana)

Answer 5

Catabolic

Question 6

• Glycerol reacts with fatty acids to make lipids

Answer 6

Anabolic

Question 7

• T/F: Enzymes can usually catalyze many reactions.
• T/F: Activation energy is lower when enzymes are present.
• T/F: Making and releasing enzymes is very energy demanding because once they do their job they cannot be used again, requiring the body to constantly make more.
• T/F: Enzymes can saturate when there is more substrate than the available enzyme can deal with.

Answer 7

F

T

F

T

Question 8

How do constitutive and inducible enzymes differ?

Answer 8

Constitutive enzymes are often enzymes that are involved in basic cellular housekeeping functions and thus are synthesized at a constant rate

Inducible enzymes are synthesized at rates that vary with the cell’s circumstances. They are produced only when needed.

Question 9

What sorts of factors influence the efficiency of enzymes?

Answer 9

• Environmental: temp and pH
• Cofactors
• Forms of inhibition: competitive and noncompetitive

Question 10

What type of inhibitor interferes with the active site of an enzyme so that its substrate can no longer bind?

Answer 10

Competitive inhibition

Question 11

Identify whether the substance travels via simple or facilitated diffusion. Also, indicate why.

O2, amino acids, Na2+, steriod hormones

Answer 11

o2 - Simple. Nonpolar and very small

amino acids - Facilitated. Too large and sometimes their solubility forbids it

Na2+ - Facilitated. It’s charged

steriod hormones - Simple. They are lipid soluble and thus able to cross

Question 12

What is the difference between active and passive transport?

Answer 12

Active transport: when items are moved up their concentration gradients – this requires energy

Passive transport: when items move down their concentration gradients – this does not require energy

Question 13

Fick Equation: calculate rate of diffusion

Answer 13

K = diffusion constant  we can’t change
A = area for gas exchange  increase in area leads to an increase in rate
P2-P1 = difference in partial pressures across membrane  increase in the difference leads to an increase in rate
D = distance (thickness of the exchange surface)  increase in distance (thickness) leads to a decrease in rate

Question 14

What two forces drive the movement of ions?

Answer 14

Electrical and chemical gradient

Question 15

What ion’s Nernst potential is resting membrane potential closest to and why?

Answer 15

K+ and this is because the resting membrane potential is dominated by K+ permeability. In other words, the cell membrane is more permeable to K+ than other ions

Question 16

Explain how the Na+/K+ pump serves as an example of an active transport method?

Answer 16

It is a protein pump found in the cell membrane and it serves to transport 3 Na+ out of and 2 K+ into the cell to help restore their concentration inside and outside of the cell.

Since this movement is against both Na+ and K+’s concentration gradient it requires energy and is thus an active method of transport.

Question 17

How do freshwater fish combat losing ions and gaining water to their environment?

Answer 17

Freshwater fish have a tendency of gaining water from and losing water to their environment given the differences of osmolarity across their membranes. Thus, they require mechanisms to maintain an internal consistency that is different than their external environment.

They do this by riding waste products across their gill surfaces (H+ and HCO3-) which involves movement down their concentration gradients. Energy captured by this movement is used to drive the movement of Na+ and Cl- up their concentration gradients into the fish.

Question 18

Ligand-gated receptor

Answer 18

Acts as both a receptor and a channel
Opens in response of binding with its specific ligand

Question 19

G protein

Answer 19

Mediates intracellular effects by activating a G protein

Question 20

Enzyme/enzyme linked receptor

Answer 20

Intracellular domain is an enzyme whose catalytic activity is regulated by the binding of an extracellular signal.

Question 21

Intracellular receptor

Answer 21

Associated with items that can cross the cell membrane

Allows them to bind to receptor inside cell