Struggle for Existence pt. 5

Question 1

organisms are…

Answer 1

bags of juices in which chemical rxns occur and libraries of info (DNA)

Question 2

Abiotic factors can be divided into

Answer 2

conditions
- cannot be depleted (temp, pH)
resources
- water, space, nutrients

Question 3

Limiting factors

Answer 3

determine whether a species can or cannot persist in an area
biggest two for land organisms are temp and moisture.

Question 4

transect

Answer 4

sample that cuts across ecological variation

Question 5

Factors like temp, pH, salinity, organic content of soil, altitude can be treated as….

Answer 5

a gradient

Question 6

Range of tolerance

Answer 6

the portion of an ecological gradient an organism is restricted to

Question 7

types of soil

Answer 7

hydric - wet, waterlogged
xeric - dry
mesic - mix of the two

Question 8

Why are temp and water so important?

Answer 8

Temperature affects reaction rates (proteins denature at too high, reactions will not proceed if its too cold). Water determines internal chemistry. Water will change the concentration of reactants and also affect osmotic balance

Question 9

How does equilibrium affect organisms?

Answer 9

objects will reach same temp as their surroundings, and in dry environments organisms will lose water and become saltier.

Question 10

Why is equilibrium asymmetrical?

Answer 10

Environments are intrinsically implacable and organisms are intrinsically vulnerable (rabbit in the arctic becomes super cold but the heat lost by the rabbit does not affect the arctic at all)

Question 11

thermoregulation

Answer 11

maintaining temp

Question 12

osmoregulation

Answer 12

maintaining saltiness

Question 13

thermoconformers

Answer 13

organisms whose bodies closely track ambient temperatures

Question 14

Which is a better median for heat exchange: water or air?

Answer 14

Water because it requires more energy than any other material commonly found in ecosystems to change its temperature.

Question 15

radiative heat transfer

Answer 15

does not involve heat transfer by molecules crashing into each other. Concept that you can be heated by a net positive difference in the IR energy being radiated from towards you than from you. Fire on a cold night doesn’t warm your back because it’s not warming the environment!!

Question 16

linear dimensions

Answer 16

length, width, height

Question 17

How do otters and penguins stay warm in water?

Answer 17

Water is really effective at conducting heat out of animals. Otters and penguins keep fur/feathers temporarily waterproof by oil secretions and preening. Mammals that are continually immersed need blubber (their outer skin is equilibrated with water but inside is warm)

Question 18

How do birds stay so warm?

Answer 18

Puff up contour feathers, creates empty space where down feathers spring up blocking convective air flow that brings hot air away from skin.

Question 19

countercurrent circulation

Answer 19

direct contact between arteries and veins

Question 20

Most homeotherms can survive extreme cold if… and heat if…

Answer 20

they have sufficient food

they have sufficient water

Question 21

kangaroo rats

Answer 21

Survive without every drinking liquid water, instead use metabolic water produced by oxidizing dry food they eat. They have highly efficient kidneys that secrete really concentrated urine (minimal water loss). Hygroscopic seeds absorb moisture exhaled.

Question 22

Catch-22 of leaves

Answer 22

need to be big enough to catch photons and facilitate gas exchange but the larger the leaf the more prone to overheating (leaves are thin thus little if any thermal inertia)
- they use evaporative cooling (water from roots goes to leaves)

Question 23

C3 plants

Answer 23

• atmospheric CO2 is fixed in a three carbon molecule (enzyme that captures carbon is not efficient and sometimes captures oxygen instead)
• not water efficient
• stomata must be open when sunlight hits to facilitate gas exchange
• wheat and rice

Question 24

C4 plants

Answer 24

• tropical grasses (maize, sugar cane)
• 4 carbon intermediate
• stomata must be open when sunlight hits to facilitate gas exchange

Question 25

CAM

Answer 25

Crassulacean Acid Metabolism

• extreme water conservation in succulents and epiphytes
• thick leaves that provide inertia
• keep stomata closed during sunny periods and open at night to get CO2
• store CO2 in vacuoles as organic acid intermediate until the next day
• when photons are available, acid continues on pathway
• evolved independently in many species

Question 26

Why do leaves have lobes and points and bumps

Answer 26

to turn laminar airflow into turbulent air flow to facilitate gas exchange (break up boundary surface layer thats stagnant air)

Question 27

differing root systems

Answer 27

• deep root systems use water stored deep in the soil (soil is external store)
• extensive, shallow root systems like the saguaro cactus occur in environments where the soil is dry except right after it rains. The root system immediately soaks up as much water as possible as soon as it falls (internal store year round)

Question 28

How do other desert plants survive (not cacti)?

Answer 28

They grow, flower, and seed right after a rain. They only grow in periods where there is non-desertlike conditions.

Question 29

microphylly

Answer 29

tiny leaves

Question 30

Sclerophylly (advantages in multiple habitats)

Answer 30

small, thick, tough, leaves that persist year round. smelly. (rosemary, pine needles)
BOREAL
- evergreens dont have to regrow leaves and can photosynthesize as soon as its warm enough
- good at shedding snow

CHAPARRAL
- small leaves less likely to overheat also need less water for evaporative cooling

SANDY SOIL

• soil is bad at retaining water, this can have desert like conditions
• dont have to regrow leaves in nutrient deficient conditions

BOGS
- favoured indirectly in acidic watery conditions that pickle dead vegetation (stopping nutrient release) because being evergreen increases nutrient retention

Question 31

Angiosperm

Answer 31

Flowering plants, seeds enclosed within an ovary (usually fruit)

Question 32

Gymnosperm

Answer 32

Conifers

• seed bearing, vascular plants
• no flowers or fruits
• have unenclosed (naked) seeds on the surface of scales or leaves