Plant Form and Function Study Guide

Plant Form and Function Study Guide

Environmental Energy Mismatch Case-study Caribou migration triggered by day-length temp. has sped up plant sprouting in the spring Now plant nutrition and digestibility have peaked before the arrival of caribou There is a mismatch in timing between new plant growth and caribou birthing Without adequate nutrition for nursing, production of offspring has declined 75% since 1993

Simplified Carbon-Cycle 1. Which arrow (I or II) is photosynthesis? Which is respiration? 2. When a plant grows and gains mass, where does that mass come from? 3. What would happen to a plant s mass if it was kept in the dark for two days? What chemical reaction is responsible? Where would the mass go?

Simplified Carbon-Cycle 1. I is photosynthesis and II is cellular respiration 2. When a plant grows, mass is added as CO 2 is assimilated during photosynthesis 3. If a plant was kept in the dark, it would continue to perform cellular respiration (to maintain homeostasis), which would breakdown stored starch/sugar and release CO 2 gas, the plant would lose mass (and photosynthesis could not be performed)

Predict how the following treatments would affect the rate of germination? Justify each prediction: 1. Temperature: cold, warm, boiling 2. Environment with/without oxygen 3. Environment with/without light

During germination, cellular respiration recycles ATP that is required for cell-division (growth), no photosynthesis occurs until the first leaves (and chlorophyll) are produced. 1. Increasing temperature should increase the rate of the chemical reaction of cellular respiration, and thus increase the rate of germination; however, boiling will result in enzymes denaturing and will thus kill the embryo. 2. Cellular respiration requires oxygen, and thus it can not occur, and germination would thus cease in an environment without oxygen. 3. Germination involves cellular respiration, not photosynthesis, and thus does not require light.

1. What is the effect of the plant hormone ethylene on fruit ripening? 2. How does fruit change as it ripens? 3. What is the mechanism behind ripening? 4. Why does fruit ripen faster if placed in a paper bag?

1. What is the effect of the plant hormone ethylene on fruit ripening? Ethylene appears to stimulate fruit ripening 2. How does fruit change as it ripens? Acids neutralized, starch turned to sugars, chlorophyll breaks down, fruit becomes soft and more fragrant 3. What is the mechanism behind ripening? Ethylene appears to act as a signal (hormone) molecule that activates a series of enzymes 4. Why does fruit ripen faster if placed in a paper bag? A paper bag likely traps the ethylene, allowing it to build up to a larger concentration

1. When is the embryo only performing cellular respiration? 2. Why does it need to do this? 3. Why does the stem need to elongate? 4. What is needed for chlorophyll production and why? 5. When does photosynthesis start?

Cellular respiration for growth ( cell #) using starch/oils stored in seed. Stem elongation to get plant above ground When exposed to light, chlorophyll is produced and photosynthesis can start (respiration continues)

Predict the effect of the loss of decomposers (bacteria and fungi) on the chemical cycling of matter in ecosystems.

Without decomposers (bacteria and fungi) dead organic material (detritus) would not be broken down and the nutrients locked away in this material would not be released into the environment for new plant growth plant growth would likely decrease.

Data on date of emergence of butterflies from the chrysalis: 1. What has been the trend in when butterflies emerge from 1840 to 2010? 2. What has been the trend in mean April October temperatures from 1940 to 210? 3. Suggest how these two data sets are connected:

Data on date of emergence of butterflies from the chrysalis: 1. Now, butterflies emerge earlier than they did historically (circa 1940). 2. The mean temperature has increased from 1940 to 2010. 3. An increase in temperature likely speeds up the process of metamorphosis, allowing butterflies to emerge earlier than they did historically.

Predict the effect of ground-cover (shading by vegetation) on soil temperature. Describe what a graph of these two variables would look like. Explain how fire in an environment could affect soil temperature. Soil Temperature (⁰C) As ground-cover (shading vegetation) is reduced, soil temperature would be expected to increase during warm, sunny days because more sunlight would reach the soil s surface. Fire would be expected to clear away vegetation and thus result in warmer soil surfaces. Ground-cover (vegetation)

Describe & explain the relationship between the variables from 0 60% open stomata. Do the same for >60% open stomata.

For which type of plant would you expect to find: Stomata on both top and bottom leaf surfaces No stomata Stomata only on the top Justify your selection:

For which type of plant would you expect to find: Stomata on both top and bottom leaf surfaces Emergent plant such as the cattails because both surfaces are exposed to air and the stomata are necessary for gas-exchange but also help to limit water-loss due to transpiration. No stomata The aquatic plant will do gas exchange via diffusion of gases from water through the entire leaf surface area. Water is also not limiting because the plant is submerged. Stomata only on the top The water lily only has its upper surface exposed to air. Here it will want to control water-loss via stomata regulation. The bottom surface is exposed to water, plant does not have to control for water loss here.

Why do many terrestrial plants have stomata only on the bottom of their leaves (or more on the bottom than top)?

Why do many terrestrial plants have stomata only on the bottom of their leaves (or more on the bottom than top)? The top of the leaves are exposed to more sunlight, which would speed evaporation from stomata. Concentrating stomata on the leaf bottoms helps to slow water loss via transpiration.

1. Show a graph of the relationship between temperature and the rate of transpiration (make sure you label your axes) 2. Discuss the mechanism by which temperature effects the rate of transpiration:

As temp., kinetic energy of molecules, thus the speed of diffusion (evaporation of water from stomata openings) will increase. At a certain temp. the rate will level off because other factors now limit the rate of transpiration.

1. Show a graph of the relationship between relative humidity and the rate of transpiration (make sure you label your axes and note that relative humidity runs on a scale from 0 to 100%) 2. Discuss the mechanism by which humidity effects the rate of transpiration:

As relative humidity, transpiration rate, because as humidity, the gradient in Ψ between the leaf and the air, thus water loss.

As % open stomata from 0 to 60, so does the rate of transpiration because with more stomata open there is diffusion between the leaf and the environment. Above 60%, there is no change in the rate of transpiration because another factor becomes limiting (i.e. rate of water movement, humidity, etc.).

1. Show a graph of the relationship between light intensity and the rate of transpiration (make sure you label your axes) 2. Discuss the mechanism by which light intensity effects the rate of transpiration:

The effect of light on the rate of transpiration Light is needed to drive the process of photosynthesis. As light intensity increases, so does the rate of photosynthesis until light is no longer limiting to the reaction. As the rate of photosynthesis increases, the demand for CO 2 also increases, and more stomata must open to meet the demand.

1. What is the effect of wind on the rate of transpiration? 2. Discuss the mechanism by which wind effects the rate of transpiration:

Boundary layer of high humidity, difference in Ψ inside and outside the leaf is, so transpiration rate Wind blows away boundary layer Difference in Ψ (or osmotic potential) inside and outside the leaf, so transpiration rate