Lab Material (Exam 1)

Question 1

Questions in Ecology take on one of these three forms

Answer 1

1. What happens if?
2. How does something happen?
3. Why does something happen?

Question 2

Proximate causes

Answer 2

immediate or direct causes (ex: environmental factors/physiological mechanisms)
these are usually the how questions

Question 3

Ultimate causes

Answer 3

explain evolutionary/historical forces that produced responses
these are usually the why questions

Question 4

Two most important measurements in aquatic systems

Answer 4

temperature & dissolved oxygen content

Question 5

saturation level

Answer 5

the point where the dissolved oxygen concentration is at equilibrium with the atmospheric oxygen

Question 6

oxygen content can be expressed in these two ways

Answer 6

1. concentration (mg/L)
2. percent saturation

Question 7

% saturation formula

Answer 7

(oxygen in pool/oxygen at saturation ) * 100

Question 8

Oxygen level greater than saturation level indicates

Question 9

Oxygen concentration can be increased by:

Answer 9

photosynthesis performed by plants & algae

Question 10

oxygen concentration can be decreased by:

Answer 10

demand for oxygen by abiotic chemical reactions & increased rates of respiration

Question 11

what does an oxygen level about 100% saturation imply?

Answer 11

oxygen is being added to the water faster than it can equilibrate with teh atmosphere

Question 12

oxygen levels below 100% saturation imply:

Answer 12

oxygen is being consumed faster than it’s being added

Question 13

Abiotic factors that influence oxygen content include

Answer 13

temperature (colder water holds more dissolved oxygen)
salnity: higher salinity REDUCES dissolved oxygen
pressure: increased pressure results in more oxygen
water flow (increased movement can increase oxygen)
light availability (sunlights –> more photosynthesis –> more oxygen)

Question 14

Biotic factors influencing oxygen content include

Answer 14

1. Plants, algae, certain bacteria perform photosynthesis and produce oxygen
2. Fish, aquatic invertebrates consume oxygen during respiration
3. Decomposers: bacteria and fungi break down organic matter, and this uses oxygen
4. Density: more organisms can increase oxygen consumption bc of increased respiration

Question 15

respiration formula

Answer 15

carbohydrate + O 2 ® energy + CO 2 + H2 O

Question 16

photosynthesis (general fomrula)

Answer 16

CO 2 + H2 O + solar energy ® carbohydrate + O 2

Question 17

Light-dependent reaction formula

Answer 17

H2 O + solar energy ® O 2

Question 18

calvin cycle formula:

Answer 18

CO 2 ® carbohydrate

Question 19

How will values change during the day? When will oxygen levels be highest vs. lowest

Answer 19

oxygen levels should be highest in late afternoon bc sunlight is driving photosynthesis
- lowers at night (no sunlight but continuation of respiration)

Question 20

what instrument did we use during the observation lab

Answer 20

dissolved oxygen meter