Answer:
Sometimes molecules cannot move through the cell membrane on their own. These molecules need special transport proteins to help them move across the membrane. Facilitated diffusion is the diffusion of substances with the help of transport proteins in the plasma membrane. These special proteins are called channel proteins or carrier proteins, and they are attached to the cell membrane. In fact, they go through the cell membrane, from the inside of the cell to the outside. Facilitated diffusion is used for molecules that cannot diffuse rapidly through cell membranes on their own, even when the molecules are moving from high to low concentration areas. An example is the sugar plants and animals use for energy, called glucose. Even though facilitated diffusion involves transport proteins, it is still passive transport because the solute is moving down the concentration gradient so it does not require the use of cellular energy.
Answer:
a.Many mitochondrial genes resemble proteobacteria genes, while the genes in the chloroplast resemble genes found in some photosynthetic bacteria.
c.Mitochondria and chloroplasts both have their own circular DNA and 70S ribosomes that are similar to those found in bacteria.
d.Mitochondria and chloroplasts replicate by a process similar to mitosis.
Explanation:
Endosymbiotic theory states that mitochondria and chloroplast which are organelles of eukaryotic cells were once independently living micro-organisms but with due course of time eukaryotic cells engulfed them and they become an integral part of these eukaryotic cells.
The resemblance between mitochondrial genes with those of proteobacteria and chloroplast genes with photosynthetic bacteria strongly support endosymbiotic theory. Apart from this, the presence of their own DNA that too circular just like prokaryotic microbes and 70 S ribosomes also support this theory. Also just like prokaryotic cells, before cell division mitochondria and chloroplasts undergo replication by means of a process known as binary fission.
