How is photosynthesis similar in C4 plants and CAM plants? (A) In both cases, only photosystem 1

step 1 Let's walk through the photosynthesis in C4 plants and cam plants. So first we'll start with the

How is photosynthesis similar in C4 plants and CAM plants?...

How is photosynthesis similar in $\mathrm{C}_{4}$ plants and CAM plants? (A) In both cases, only photosystem 1 is used. (B) Both types of plants make sugar without the Calvin cycle. (C) In both cases, rubisco is not used to fix carbon initially. (D) Both types of plants make most of their sugar in the dark.

How is photosynthesis similar in $\mathrm{C}_{4}$ plants and CAM plants?
(A) In both cases, only photosystem 1 is used.
(B) Both types of plants make sugar without the Calvin cycle.
(C) In both cases, rubisco is not used to fix carbon initially.
(D) Both types of plants make most of their sugar in the dark.

Key Concepts

CAM Photosynthesis

CAM (Crassulacean Acid Metabolism) photosynthesis is an adaptation that allows plants to fix CO2 at night using PEP carboxylase to form organic acids, which are then decarboxylated during the day to release CO2 for the Calvin cycle. This temporal separation of carbon fixation helps reduce water loss in arid conditions.

Photosynthesis

Photosynthesis is the biological process by which plants, algae, and some bacteria convert light energy into chemical energy, storing it in the bonds of sugar molecules. This process involves the absorption of light by pigments, the generation of ATP and NADPH, and the fixation of carbon dioxide into organic compounds.

Carbon Fixation Mechanisms

Carbon fixation refers to the process of converting inorganic carbon dioxide into organic molecules during photosynthesis. Different groups of plants employ distinct mechanisms to initially capture and convert CO2, particularly in adapting to environmental conditions such as high temperatures or water scarcity.

Rubisco

Rubisco is the enzyme that catalyzes the incorporation of carbon dioxide into the Calvin cycle during photosynthesis. While it plays a central role in the carbon fixation of many plants (such as those using the C3 pathway), certain adaptations in other plants involve alternative enzymes for the initial carbon fixation steps.

C4 Photosynthesis

C4 photosynthesis is an adaptation found in some plants where CO2 is initially fixed by phosphoenolpyruvate carboxylase (PEP carboxylase) rather than Rubisco, forming a four-carbon compound. This mechanism minimizes photorespiration and increases photosynthetic efficiency under conditions of high light intensity, temperature, and dryness.

Transcript

00:01 Let's walk through the photosynthesis in c4 plants and cam plants.

00:09 So first we'll start with the c4 plants.

00:13 So in c4 plants, the light dependent reactions and the calvin cycle are physically separated.

00:20 With the light dependent reactions occurring in the mesophyll cells, which is the spongy tissue in the middle of the leaf, and the calvin cycle occurring in special cells around the leaf veins.

00:31 And those cells are called bundle sheath cells.

00:36 So to see an example of c4 photosynthesis, let's draw a little diagram.

00:51 So first, atmospheric carbon dioxide is fixed in the mesophyll cells to form a simple four -carbon organic acid or oxaloacetate.

01:10 So there is our oxaloacetate right there.

01:16 This step is carried out by a non -rubisco enzyme.

01:20 The pep carboxalis, which is right here, and it has no tendency to bind to oxygen or o2.

01:29 Oxycala acetate is then converted to a similar molecule, malate, and that can be transported into the bundle sheath cells, which is here.

01:45 Inside the bundle sheath, the malate breaks down, releasing a molecule of carbon dioxide.

01:54 That carbon dioxide is then fixed by rubisco and made into short.

01:58 Via the calvin cycle, very similar to other plants.

02:04 Calvin cycle, and there is our sugars.

02:13 And now let's look at the cam plants.

02:19 So cam plants are adapted to dry environments like cacti and pineapples, and they use the crosilician acid metabolism or cam pathway, which minimizes photorespiration.

02:33 So instead of separating the light -deprients, reactions and the use of carbon dioxide in the calvin cycle in space, cam plants separate these processes in time...

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