What types of plants are C4 and CAM?

Answer 1

C4 Plants

Over 8000 species of angiosperms, scattered among 18 different families, have developed adaptations which minimize the losses to photorespiration.
They all use a supplementary method of CO2 uptake which forms a 4-carbon molecule instead of the two 3-carbon molecules of the Calvin cycle. Hence these plants are called C4 plants. (Plants that have only the Calvin cycle are thus C3 plants.)

* Some C4 plants — called CAM plants — separate their C3 and C4 cycles by time. CAM plants are discussed below.
* Other C4 plants have structural changes in their leaf anatomy so that
o their C4 and C3 pathways are separated in different parts of the leaf with
o RUBISCO sequestered where the CO2 level is high; the O2 level low.
These adaptations are described now.

The details of the C4 cycle

* After entering through stomata, CO2 diffuses into a mesophyll cell.
o Being close to the leaf surface, these cells are exposed to high levels of O2, but
o have no RUBISCO so cannot start photorespiration (nor the dark reactions of the Calvin cycle).
* Instead the CO2 is inserted into a 3-carbon compound (C3) called phosphoenolpyruvic acid (PEP) forming
* the 4-carbon compound oxaloacetic acid (C4).
* Oxaloacetic acid is converted into malic acid or aspartic acid (both have 4 carbons), which is
* transported (by plasmodesmata) into a bundle sheath cell. Bundle sheath cells
o are deep in the leaf so atmospheric oxygen cannot diffuse easily to them;
o often have thylakoids with reduced photosystem II complexes (the one that produces O2).
o Both of these features keep oxygen levels low.
* Here the 4-carbon compound is broken down into
o carbon dioxide, which enters the Calvin cycle to form sugars and starch.
o pyruvic acid (C3), which is transported back to a mesophyll cell where it is converted back into PEP.

These C4 plants are well adapted to (and likely to be found in) habitats with

* high daytime temperatures
* intense sunlight.

Some examples:

* crabgrass
* corn (maize)
* sugarcane
* sorghum

C4 cells in C3 plants
The ability to use the C4 pathway has evolved repeatedly in different families of angiosperms. Perhaps the potential is in them all.

A report in the 24 January 2002 issue of Nature (by Julian M. Hibbard and W. Paul Quick) describes the discovery that tobacco, a C3 plant, has cells capable of fixing carbon dioxide by the C4 path. These cells are clustered around the veins (containing xylem and phloem) of the stems and also in the petioles of the leaves. In this location, they are far removed from the stomata that could provide atmospheric CO2. Instead, they get their CO2 and/or the 4-carbon malic acid in the sap that has been brought up in the xylem from the roots.

If this turns out to be true of many C3 plants, it would explain why it has been so easy for C4 plants to evolve from C3 ancestors.
CAM Plants
These are also C4 plants but instead of segregating the C4 and C3 pathways in different parts of the leaf, they separate them in time instead. (CAM stands for crassulacean acid metabolism because it was first studied in members of the plant family Crassulaceae.)

At night,

* CAM plants take in CO2 through their open stomata (they tend to have reduced numbers of them).
* The CO2 joins with PEP to form the 4-carbon oxaloacetic acid.
* This is converted to 4-carbon malic acid that accumulates during the night in the central vacuole of the cells.

In the morning,

* the stomata close (thus conserving moisture as well as reducing the inward diffusion of oxygen).
* The accumulated malic acid leaves the vacuole and is broken down to release CO2.
* The CO2 is taken up into the Calvin (C3) cycle.

These adaptations also enable their owners to thrive in conditions of

* high daytime temperatures
* intense sunlight
* low soil moisture.

Some examples of CAM plants:

* cacti
* Bryophyllum
* the pineapple and all epiphytic bromeliads
* sedums
* the "ice plant" that grows in sandy parts of the scrub forest biome

C4 Diatoms
On 26 October 2000, Nature reported the discovery of both the C3 and C4 pathways in a marine diatom. In this unicellular organism, the two paths are kept separate by having the C4 path in the cytosol, and the C3 path confined to the chloroplast. The presence of a C4 pathway probably reflects the frequent low concentrations of CO2 in ocean waters.

Answer 2

C4 plants are typically tropical grasses - the ones you will be seeing most often include corn, crab grass, Bermuda grass, and Saint Augustine grass. C4 plants include several thousand species in at least 19 plant families, everything from fourwing saltbush to many of our summer annual plants.

CAM was first discovered in Crassulaceae plants, such as Crassula (including the Jade plant), and named for the product found - 'Crassulacean Acid' [malate] Metabolism. CAM plants include many succulents such as cactuses and agaves and also some orchids and bromeliads.

Answer 3

C4 plants only open their stomata (the little openings that let the plant 'breathe' on the underside of the leaves) halfway to prevent water loss in a dry climate.
CAM plants live in really hot, arrid climates like deserts. They only open their stomata at night when it is cooler so they don't lose water during the day.
This is a basic high school biology answer (I can't believe i remembered this!) i hope it's enough. I know this is correct, by the way.

Answer 4

C4 plants are mostly tropical grasses (sorghum, maize, sugarcane)

CAM plants are mostly desert plants (cacti and succulents and pineapple)

Answer 5

They are both photosynthetic plants.

Answer 6

erm.... bombs...