Lecture 4: Physiological ecology

Question 1

What are hermaphrodites’?

Answer 1

Flowers that have both male and female parts (roughly 90%)

Question 2

What are stigma and anthers? and what do they contain?

Answer 2

Stigma is the female part (recieves pollen)
Anthers are the male parts, which contain pollen

Question 3

What does sessile mean?

Answer 3

Plants can’t move, which is known as sessile.

Question 4

What is key for plants?

Answer 4

Carbon balance: Gaining more carbon through photosynthesis than lose through respiration.

Question 5

What is carbon sink?

Answer 5

Plants taking in carbon dioxide and storing them in their tissues.

Question 6

What is NPP?

Answer 6

It is net primary productivity.

Carbon gained - carbon loss from respiration

Question 7

Why are some stems green?

Answer 7

Because they contain chlorophyll.

Question 8

What is transpiration?

Answer 8

Water loss through stomata.

Question 9

What are benefits and costs of having large surface area in a leaf? ie SA/V ratio.

Answer 9

Benefits: More sunlight, hence more production of CO2.

Costs: If a plant lives in hot climate, they need to save water from solar radiation. Humans generate heat, but plants don’t hence more SA/V ratio means that more loss of water in plants.

Question 10

What method do most plants use for producing carbon?

Answer 10

C3, where the first compound produced is three carbon molecule.

Question 11

Why is Rubisco bad?

Answer 11

At high temp, rubisco accepts O2 instead of CO2 which means the plant has to do photorespiration.

Question 13

How have plants evolved to reduce photorespiration?

Answer 13

1. C4 plants: PEP carboxylase (has higher affinity to CO2) accepts CO2, reducing photorespiration
2. CAM plants: Close stomata during day, and open at night for CO2 and convert it into malate, which is used in the day to perform photosynthesis in the presence of light.

Question 14

How do plants deal with overheating?

Answer 14

1) Grow in shady regions
2) Open and close stomata, to take advantage of evaporative cooling.

3) Keep stomata closed under drought condition

Question 15

What hormone is responsible for opening and closing of stomata?

Answer 15

ABA or abscisic acid

Question 16

What are the tradeoffs plants face?

Answer 16

It is rapid growth or water conservation.

1) Close stomata and stop plant growth, risk overheating (because evaporative cooling isn’t available), stutting of all gas exchange (No co2 input)

2) Open stomata, but risk water loss.

Question 17

What is the adaptation in Palo Verde?

Answer 17

Has very small leaves that are shed off in dry climate, while all the photosynthesis is performed by the stem.

Question 18

What does Microphylly mean?

Answer 18

small leaves (in latin)

Question 19

why are leaves bigger in warm climate, while some leaves are small?

Answer 19

It depends on the rainfall, it is not how hot it is, it is how wet it is.

Question 20

How has opuntia santa-rita adapted to reduce water loss.

Answer 20

1) Microphylly to extreme-no leaves

2) flat, which means at mid-day sun only shines on the corners not on the entire leaf

3) At sun set and sun rise, they are angled towards the sun.

Question 21

How has Saguaro adapted to episodic rains? while being restricted to Sonoran dessert?

Answer 21

-Grow extremely slowly
-live 200+ years
-extensive but shallow roots
-800L of water is absorbed from one storm
-Accordion pleated truck allows for expansion
-Mnemonic digression (David Grundman)

Question 22

Why are cactus roots shallow?

Answer 22

When rain falls, it does not penetrate deep, hence it stays at the top, which can be absorbed by the cacti.

Question 23

Why do tropical trees have shallow roots?

Answer 23

Rain fall leeches out all the nutrients, hence low minerals are available deep. But the top layer has a lot of leaves which replenish the soil.

Question 24

What is forging?

Answer 24

Important behavior, seeking shelter, food etc.

Question 25

What is root forging?

Answer 25

Using split root experiment to see how roots grow.

Roots know where there is more nitrogen and where there is low nitrogen.

Question 26

What did the graphs represent for the legumes plants (root forging)

Answer 26

X: Nitrogen treatment and Symbiont treatment

Y: Root biomass and root nodules

There was more biomass in high nitrogen and more nodules in effective n treatment.

Question 27

What is the difference between laminar and turbulent flow?

Answer 27

laminar: Smooth and laminar air flow of wind

turbulent: Turbulent air flow

Question 28

Why is laminar air flow not present in leaves?

Answer 28

Because it can cause build up and clog the pores.

Turbulent air flow, promotes gas exchange, like cooling leaves turbulent airflow is better

Question 29

What is morphological plasticity?

Answer 29

the same tree having different shaped leaves, some turbulent, while some laminar.

Turbulent at the top (to promote gas exchanges, evaporative cooling in warm temp) while laminar leaves in shady area.

Question 30

What is recursive digression?

Answer 30

Convective cooling by aided by turbulence. like arctic hare having sleek shape, by which air flows smoothly.

Question 31

What are epiphytes?

Answer 31

Plants that are not rooted in soil, but they grow on other trees.

cacti are also epiphytes, they can grow in rainforests struggling with water stress.

Question 32

What are adaptations unique to epiphytes?

Answer 32

-having tanks in between, catching water like pineapple (bromeliads)

-Has animals growing in them, sometimes captures leaves, which decompose
giving nutrients.