Yes, during intense exercise, muscles cell may use fat as a concentrated source of chemical energy. When oxygen is present, the fatty acid chains containing most of the energy of a fat are oxidized and fed into the citric acid cycle and the electron transport chain. Nonetheless, during intense exercise, oxygen is scarce in muscle cells, so ATP must be generated by glycolysis alone.
Answer:
plicae circulares and intestinal villi
Explanation:
The inner wall of the intestine is full of wrinkles, called villi. An enlargement of them under the microscope reveals that they are formed by cells whose surface has innumerable small "wrinkled" structures. The small intestine is the largest viscera of the body (about six meters). Intestinal villi and microvilli increase the area of contact with the intestine as well as the speed of absorption of food. Blood capillaries and lymph are in these villi to absorb nutrients.
The intestinal villi, have the function of increasing the absorption of nutrients after digestion. They are the folds of the intestines. The surface of the villi has an area of 12 cm² and the microvilli 240 cm².
Villi and microvilli increase the area of intestinal absorption by approximately 30 times and 600 times, respectively, providing exceptionally efficient absorption of nutrients in the lumen.
The entire small intestine has circular folds of mucosa, also called Kerckring valves and circular plicae. Most extend transversely around the small intestine cylinder for about half or two-thirds of its circumference, but some form complete circles, and some have a spiraling direction; The latter usually extend a little more than once around the bowel, but occasionally two or three times. Circular folds slow the passage of partially digested food along the intestines and provide an increased surface for absorption.
The mutation in the sperm cell could be passed on to offspring, while the skin cell mutation could only affect the individual.
Answer:
Single celled or unicellular organisms use simple processes such as diffusion and active transport to gain nutrients. iii) Unicellular organism requires less energy and makes use of simple process such as diffusion to perform gas exchange.
Explanation:
Answer:
variation in skin color.
Explanation:
The human skin color is determined genetically depending on the amount of melanin. However pigmentation can occur as a results of exposure to uv rays that causes induced pigmentation.
The sun emits two types of ultra violet rays which can reach can reach the skin namely the uva and uvb. Both type of rays can damage the skin if unprotected. Due to this there was evolution against the damaging rays. More melanin that provides a natural sunscreen to the people leaving in the tropic environment.
