Category: Botany FAQ’s

As described in the beginning of this question, collenchyma cells are found in young stems and petioles (leaves) and function to provide flexible support to the plant. This is because chollenchyma cells lack secondary cell walls and do not produce lignin to harden them—this protein is characteristic of sclerenchyma cells, which are also used to provide support/strength to the plant. 

Due to their lack of rigidity, collenchyma cells a also capable of elongating with the stems and leaves they support, allowing them to remain alive at maturity. Sclerenchymal cells lack this ability.

The periderm forms a protective layer around the outside of many stems and roots and consists of cork cambium, cork, and phelloderm. Cork cambium is the site of active secondary growth within the periderm of vascular plants. Phloem is a type of vascular tissue that directs the flow of nutrients and metabolic products from the leaves down to the roots.

A plant’s vascular tissues transport nutrients throughout the plant, just as the circulatory system transports nutrients throughout human bodies. While blood is the primary solvent for nutrients in humans, water is the primary solvent for nutrients in plants. Animals, however, use blood pressure to propel nutrients throughout the body while plants use gravity and the cohesive properties of water to transport nutrients.

The two primary types of plant vascular tissue are xylem, which transports water, and phloem, which transports organic molecules like glucose.

The stoma allows for gas exchange and transpiration. The stoma usually opens following stimulation by sunlight and closes in low water environments. Other answers are parts of a typical plant, however do not play a role in gas exchange or transpiration.

The vascular system in plants is designed to transport materials (water, nutrients, food) between the roots and shoots. There are two primary types of tissue dedicated to these processes. Xylem transports water and dissolved minerals upward from the roots; phloem transports sugars—the products of photosynthesis—from where they are synthesized to where they are needed, such as roots and new growth areas of leaves and fruits.

Both xylem and phloem are comprised of a variety of cell types that are specialized for transport and support. 

The Calvin Cycle occurs in the stroma, the aqueous fluid-filled area of the chloroplast. The stroma can be seen as analogous to the cytoplasm of a cell, in that it is the liquid in which all other substructures reside. The other processes of photosynthesis, the light-dependent reactions, take place in the thylakoid, a membrane-bound substructure within the chloroplast.

Chloroplasts, the site of photosynthesis, are only in plant cells and are not found in animal cells. Ribosomes, a cell membrane, and a mitochondria, however, can be found in both animal and plant cells.

The other structure that may be found in plant cells, but not animal cells, is a cell wall.

Chloroplasts are organelles in plant cells that conduct photosynthesis; therefore they are unique to plant cells. All the other mentioned organelles can be found in both animal and plant cells.

Split water to create a high concentration of hydrogen ions.

Explanation:

Photosystem II splits water into hydrogen and oxygen. Hydrogen ions accumulate in the thylakoid space, creating an electrochemical concentration gradient. Due to this gradient, hydrogen ions pass through ATP sythase, powering the synthesis of ATP from ADP + P_i. 

stroma . . . whenever the appropriate nutrients are present.

Explanation:

The Calvin cycle takes place in the stroma of the chloroplast, which is the region in the chloroplast lumen outside of the thylakoids. It does not actually matter whether or not light is present for the reactions of the Calvin cycle to take place. They are light independent, but light will not prevent the reactions from occurring, similar to how glycolysis is independent of oxygen. As long as the appropriate nutrients and reactants are present, including ATP and NADPH generated from the light reactions, the Calvin cycle will occur.