Answer:
B) Nitrogen-fixing bacteria and lightning
Explanation:
Nitrogen cycle is the natural process in which atmospheric nitrogen is converted into nitrite and nitrate with the help of bacteria.
Nitrogen cycle is directly dependent on nitrogen-fixing bacteria and lightning.
As bacteria are responsible for most of the chemical conversion in the nitrogen cycle such as nitrogen fixation (first step) is done by soil bacteria (Cyanobacteria) that form ammonia, which is toxic to plants; nitrification in which ammonia is converted into nitrites and nitrates with the help of Nitrobacter and denitrification bacteria involve Pseudomonas, and Achromobacter which convert nitrite and nitrate into nitrogen.
The lightning breaks nitrogen molecules and allow it to combine with oxygen in atmosphere which further dissolve in rain and form nitrates.
Hence, the nitrogen cycle is most directly dependent upon nitrogen-fixing bacteria and lightning and the correct option is B.
Answer:
This is usually the first day of menstruation - the day when the uterus lining starts to be shed.
Explanation:
Four fundamental forces
<span>gravitation
electromagnetism
the weak interaction
the strong interaction.</span>
Answer: B
Explanation: During cell division, chromatin condenses to form chromosomes.
<h3><u>Answer;</u></h3>
The above statement is <u>False </u>
<h3><u>Explanation;</u></h3>
- Speciation is an evolutionary process in which new species arise. There are three types of speciation, namely; sympatric, parapatric and allopatric speciation.
- <em><u>Sympatric speciation is a pattern in which speciation occurs in the absence of a physical barrier to gene flow; ex. polyploidy arising in flowers.</u></em>
- In an Allopatric speciation on the other hand, a physical barrier arises and separates two populations, ending gene flow between them and allowing reproductive isolating mechanisms to evolve so that later if the two groups come back into contact they will no longer be able to reproduce together, therefore making them different species.
