The double membrane. It's theorized that chloroplasts used to be their own single-celled organism in the environment (and therefore with its own membrane). Then, the theory states, a larger cell took in the chloroplast by endocytosis, which involves surrounding the chloroplast in the large cell's own membrane. The chloroplast would then have two membranes surrounding it. This is similar to the thinking for mitochondria becoming an organelle as well. Hope this helps! :)
Answer: <u>The exocrine glands hormones could be ions, enzymes mucins, water or chemical compounds that aid in the normal functioning in the human body. The glands that are exocrine are multicellular or unicellular, based on the degree of complexity of the glands as well as their function. Some examples of these are the liver and the Salivary glands. </u><em>Endocrine glands are referred to as hormones. are released by cells in an interstitial liquid. Then, they disperse into the bloodstream, without having to pass through the canal system. The endocrine glands are responsible for monitoring the long-term activity of the body and affect the general metabolism and development in the human body. Some examples of these are the Pituitary Gland and the Adrenal Gland.</em>
Hope this helps!
For hundreds of millions of years, all the land of Earth was joined together in one large mass or super continent. Scientists call it Pangaea (meaning “all lands” in Greek). Then about 200 million years ago the land began to drift apart. It broke into two pieces, and scientists have called the continent in the north Laurasia and the continent in the south Gondwanaland (named by Eduard Suess, an Austrian geologist). The two large continents continued to break apart into the smaller continents that exist today. Scientists call this movement ‘continental drift’.
