Answer:
They have helical thickening of lignin in their walls to prevent collapse
Explanation:
the primary function of Xylem and its conducting vessels tracheids is to provide support and tranport water and minerals in plants.
Xylem vessels have layers of dead materials in the walls called LIGNIN. Lignin is a polymer; a very strong, hard materials that stop water passage through it,because it contains dead cells,
Therefore the presence of deposit of these strong impermeable, ligified walls in its walls prevent its collapse during mass flow of water of transpiration pull.
Answer: Mouth.
Explanation:
The mouth is known to be performing both the tasks of chemical digestion and mechanical digestion.
The food is ingested through mouth and the teeth perform the process of mechanical digestion by breaking down the food particles into smaller particles.
Then the saliva gets mixed into the food and the enzymes(amylase) present in the saliva helps in the digestion of carbohydrates.
So, mouth is the organ that performs the process of both mechanical and chemical digestion.
Answer:
Does your bio textbook show you?
Mitochondria by using cellular respiration to make ATP
The cramps can be caused due to anaerobic respiration in the muscles and lactic acid formation.
During intense physical activity the muscles become deprived of oxygen, in this condition, anaerobic respiration takes place in the muscle cells causes the formation of the lactic acid.
The physical training increases the strength of the muscles, which can help the muscles not to get tired easily. that is why, physical training is required before any marathon.
