Answer:
Stomach mucus protects the gastrointestinal cells from the damage that gastric juices can cause. Gastric juices are very acidic and without the mucus, the acid can destroy the cells and tissues inside the stomach.
Answer:
The survival of a species depends more on the population because a population contains many type of organisms of the same species. Some of them are better adapted to survive the conditions provided by the Earth and hence, they live and produce offsprings with the favourable traits. The members of a population which are not better adapted mostly do not survive.
Hence, the survival of a species depends on the population where it is living.
In order for plants to assimilate nitrogen directly into their system, the nitrogen must be in the form of nitrates. Nitrogen in the air and ammonia from decayed matter in the soil is converted to ammonium by decomposers and nitrogen-fixing bacteria. The ammonium is further nitrified to nitrates by nitrifying bacteria. Finally, the nitrates can then absorbed by the plants.