To confirm the above hypothesis, Maria should perform an experiment to prove that xylem is responsible for the transport of coloured water through the plant. This is called the ascent of sap.
A suitable plant having a tender, semitransparent stem should be selected. The root system of the plant should be cut off and the twig has to be placed half-immersed in a coloured solution of water for about one hour. Later, when the plant is observed, parallely running streaks of coloured water can be seen through the semitransparent stem and other parts of the plant indicating that the xylem is involved in the upward movement of water.
Answer:
Species separated by a physical barrier for a long time, suffer allopatric speciation, so they can not interbreed anymore.
Explanation:
Allopatric speciation consists of the geographic separation of a continuous genetic background giving place to two or more new geographically isolated populations. These separations might be due to migration, extinction of geographically intermediate populations, or geological events. In this speciation, some barriers impede genetic interchange, or genetic flow, as the two new populations that are separated can not get together and mate anymore. These barriers might be geographical or ecological.
Vicariance is the geographical separation of an original population into two or more new groups. Discontinuities in the physical environment like rivers, mountains, water, etc., are physical barriers that impede genetic flow between the separated groups.
The process of allopatric speciation involves different steps:
- The emergence of the barrier.
- Interruption in the genetic interchange
- The occurrence of new mutations and their accumulation in time in each population. Slow and gradual differentiation.
- Genetic divergence by natural selection and reproductive isolation makes it impossible for the two groups to mate even if the barrier disappears.
- Prezigotic isolation mechanisms favored by selection once occurs a secondary contact between the new species in formation.
Answer:
Although most adults won't grow taller after age 18 to 20, there are exceptions to this rule. First, the closure of the growth plates may be delayed in some individuals. If the growth plates remain open past age 18 to 20, which is uncommon, height could continue to increase.
Water is polar. Lipids are non-polar.
