Answer:
Alkali metals are any of the elements found in Group IA of the periodic table (the first column). Alkali metals are very reactive chemical species that readily lose their one valence electron to form ionic compounds with nonmetals. All elements in the alkali metal group occur in nature.
Explanation:
Answer:
d. secondary endosymbiosis.
Explanation:
- When a living cell acquires another organism that eventually becomes a part of this cell, this process is known as primary endosymbiosis.
- When an organism that has already undergone primary endosymbiosis engulfs another eukaryotic organism then this process is known as secondary endosymbiosis.
- Secondary endosymbiosis has been known to occur in plastids because of which they are surrounded by two membranes. This bilayer is present because one of the layers is the original outer membrane of the organism and the other membrane is that of the organism that has been engulfed.
