I think that the best phrase to fit into the blank is a "scientific theory".
A scientific theory is developed through experiments which use the scientific method, and a theory can be improved if additional data is available or if people provide suggestions which make the theory fit the data better.
Answer:
A. Overtillage can increase the rate of humus decomposition
Explanation:
We refer to humus as any material of an organic nature that undergoes soil degradation. Humus is very important for agriculture because it has high nutrient levels that it provides to all crops. This causes more crop productivity, increases the producer's profit and increases the number of food available to the population.
Humus is a difficult to decompose material, but under favorable conditions it can decompose quite easily. Due to the presence of large amount of burnt organic matter in the soil, it is sometimes difficult to increase the humus content, so the exhaustion of this organic matter is caused by over tillage, especially in regions of tropical and sub-tropical climate, poorly managed. farmer protection and unprotected effects of erosion.
The presence of vertebral column or notochord at any stage of life in any organism is the characteristic of vertebrate.
Explanation:
An animal is vertebrate if it fulfils the following criteria:
Presence of vertebral column or notochord.
Presence of endoskeleton or backbone.
The spinal cord runs above the vertebral column.
Humans embryo has notochord which becomes a vertebral column.
The alimentary canals end in the anus.
Mouth is present ta the anterior side of the vertebrate.
Have legs, fins or wings for movement.
Presence of a nervous system and sensory organs.
Presence of skin, lungs or gills.
Presence of a circulatory system.
Vertebrates include fish, amphibians, reptiles, birds and mammals.
Answer: Clonal progagation
Explanation:
Clonal propagation involves the production of identical individual without the fusion of germ cells. It can be multiplication through stem and other plants part such as leaves.
Strawberry as a fruits can be multiplied using the stems thus preventing the germ cells from genetic recombination that could lead to the formation of entirely new plants. It does not involve the union of male and female germ cells.
Answer:
water molecules undergo the 'tug of war' via the cohesion-adhesion theory
Explanation:
In plants specifically, a transpiration stream is formed via osmosis from roots into xylem and travels by the apoplast pathway to the leaves, where the water then evaporates from stomata into the surrounding air along the diffusion gradient. the water loss from the mesophyll cells lowers their water potential therefore water moves in via osmosis by both apoplast and symplast pathway from adjacent cells. water bonded to water= cohesion, water bonded to carbohydrates of xylem walls= adhesion. water is drawn up in tug of war-esc fashion against gravity to replace water evaporated, resulting in cohesion-adhesion theory.
