The letter a indicates the a cross section of the eudicot root. each letter marks a definite structure. letter a marks the outer layer of the root. letter b marks the small central region of the root. letter c marks a structure that surrounds the central region of the root. letter d marks a cross-like complex in the center of the vascular cylinder, which consists of big oval cells. letter e marks a layer of the vascular cylinder below the endodermis. the letter a indicates the a cross section of the eudicot root. each letter marks a definite structure. letter a marks the outer layer of the root. letter b marks the small central region of the root. letter c marks a structure that surrounds the central region of the root. letter d marks a cross-like complex in the center of the vascular cylinder, which consists of big oval cells. letter e marks a layer of the vascular cylinder below the endodermis. xylem endodermis cortex vascular cylinder epidermis

Letter A indicates the epidermis, which is the outer layer of the root.

Explanation:

The internal structure of the eudicot root consists of three concentrical layers: The epidermis, the cortex, and the central vascular cylinder.

The epidermis is the outer layer of the root. It covers the totality of the root surface, absorbs water and minerals from the soil, and protects the internal tissues.

The cortex occupies a big part of the root and its located under the epidermis. The most internal cell layer of the cortex is called endodermis.

The vascular cylinder is composed of vascular tissues -the xylem and the phloem- that is surrounded by one or more cell layers called pericycle. The xylem looks like a cross of big cells in the center, and the phloem occupies the spaces between the pericycle and the xylem.

both anaerobic and aerobic respiration use glucose (or other carbohydrates), proteins and lipids to produce atp and nadh. cell uses those energy molecules, obtained from food and   breaks them down during the chemical reactions of respiration. in anaerobic respiration, nadh is regenerated to nad+ by enzymes lactate dehydrogenase (lactate is produced, e.g. in muscle cells) or by alcohol dehydrogenase where ethanol is produced (alcohol fermentation), while in aerobic respiration, electrons from nadh are deposited in the mitochondria to regenerate nad+ (electron transport chain. anaerobic respiration produces 2 atp per molecule of glucose compared to aerobic respiration where about 38 atp molecules are produced.

"do a testcross with a homozygous recessive plant."