1. Theoretically, plants could increase or decrease the size of individual stoma

Question

1. Theoretically, plants could increase or decrease the size of individual stomata and still achieve the same result as varying the number of stomata. But they dont do this- plants only vary stomata number, not size. Why?
( long response please :) )

2. How many stomata would you expect desert plants to have relative to rain forest plants? When and for how long would these plants keep their stomata open?

3.Human activities in the past century have greatly increased the concentration of CO2 in the atmosphere. How will increasing CO2 levels affect stomata density and rate of opening/ closing? Can you think of any additional benefits to or problems for plants associated with stomata?

THANK YOUUUUUUU!!!!

Explanation / Answer

1 : Leaf stomata are the principal means of gas exchange in vascular plants. Stomata are small pores, typically on the undersides of leaves, that are opened or closed under the control of a pair of banana-shaped cells called guard cells (see figure above). When open, stomata allow CO2 to enter the leaf for synthesis of glucose, and also allow for water, H2O, and free oxygen, O2, to escape. In addition to opening and closing the stomata (stomata behavior), plants may exert control over their gas exchange rates by varying stomata density in new leaves when they are produced (such as in the spring or summer). The more stomata per unit area (stomata density) the more CO2 can be taken up, and the more water can be released. Thus, higher stomata density can greatly amplify the potential for behavioral control over water loss rate and CO2 uptake.
2: Online exhibits : The world's biomes
The desert biome
Sand dunes in Death Valley National Monument, California.
Deserts cover about one fifth of the Earth's surface and occur where rainfall is less than 50 cm/year. Although most deserts, such as the Sahara of North Africa and the deserts of the southwestern U.S., Mexico, and Australia, occur at low latitudes, another kind of desert, cold deserts, occur in the basin and range area of Utah and Nevada and in parts of western Asia. Most deserts have a considerable amount of specialized vegetation, as well as specialized vertebrate and invertebrate animals. Soils often have abundant nutrients because they need only water to become very productive and have little or no organic matter. Disturbances are common in the form of occasional fires or cold weather, and sudden, infrequent, but intense rains that cause flooding.
There are relatively few large mammals in deserts because most are not capable of storing sufficient water and withstanding the heat. Deserts often provide little shelter from the sun for large animals. The dominant animals of warm deserts are nonmammalian vertebrates, such as reptiles. Mammals are usually small, like the kangaroo mice of North American deserts.

Desert biomes can be classified according to several characteristics.
There are four major types of deserts:

Hot and dry
Semiarid
Coastal
Cold
Hot and dry desert
The four major North American deserts of this type are the Chihuahuan, Sonoran, Mojave and Great Basin. Others outside the U.S. include the Southern Asian realm, Neotropical (South and Central America), Ethiopian (Africa) and Australian.

The seasons are generally warm throughout the year and very hot in the summer. The winters usually bring little rainfall.
3 : Greenhouse gas concentrations in the atmosphere have historically varied as a result of many natural processes (e.g. volcanic activity, changes in temperature, etc). However, since the Industrial Revolution humans have added a significant amount of greenhouse gases in the atmosphere by burning fossil fuels, cutting down forests and other activities. Because greenhouse gases absorb and emit heat, increasing their concentrations in the atmosphere will tend to have a warming effect. But the rate and amount of temperature increase is not known with absolute certainty. Changes in the atmospheric concentration of the major greenhouse gases are described below:


Figure 1 - Carbon Dioxide: Click on Thumbnail for full size image

Carbon dioxide (CO2) concentrations in the atmosphere increased from approximately 280 parts per million (ppm) in pre-industrial times to 382 ppm in 2006 according to the National Oceanic and Atmospheric Administration's (NOAA) Earth Systems Research Laboratory, a 36 percent increase. Almost all of the increase is due to human activities (IPCC, 2007). The current rate of increase in CO2 concentrations is about 1.9 ppmv/year. Present CO2 concentrations are higher than any time in at least the last 650,000 years (IPCC, 2007). See Figure 1 for a record of CO2 concentrations from about 420,000 years ago to present. For more information on the human and natural sources of CO2 emissions, see the Emissions section and for actions that can reduce these emissions, see the What You Can Do Section.

i hope it helps you :))

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