Answer:
Genes are made of DNA and are carried on chromosomes
Explanation:
Answer: exocrine glands
Explanation: Exocrine gland secrete substances to an epithelial surface through a channel.
The sebaceous and sweat glands associated with the skin also secrete substance to skin surfaces via ducts/ channels and are classified as endocrine gland. There are two glands in the human body Exocrine gland and Endocrine gland.
Endocrine gland secrete substance into the bloodstream directly. Examples of exocrine glands are sweat, salivary, mammary, sebaceous, and mucous.
liver and pancreas are both exocrine and endocrine glands simultaneously.
As exocrine gland, the liver secrete bile and the pancrease secrete pancreatic juice into the gastrointestinal tract through channels. While as endocrine gland they secrete other substances directly into the bloodstream.
Chemical bonds form between their atoms, the result is a chemical compound
Answer:
Darwin's theory of natural selection lacked the physical proof of the intermittent species as suggested by him. The fossils of such species had not been discovered by the time he wrote his book 'Origin of species'. In order to defend his theory, he pointed out the non-reliability on fossils.
Explanation:
The field of geology was just evolving at the time Darwin wrote his book, and no fossils supporting his theory has been discovered yet. He defended his theory by saying that the fossils cannot be depended on for the proof of evolution as the the process of fossilization depends on many factors, and the available fossils are very rare. The irregularities in the geological records, also suggested that the fossil records are not perfect.
Defending his theory, he shows how, if available. the fossil records can support his theory. The fossils should show the features of both the extinct (parent species ) species and the present species, as the species present in today's world have evolved from the ones that existed long before them through the process of natural selection.
The discovery of the Archaeopteryx in 1861 supported his theory and the process of evolution as it showed the features of both the reptiles and birds.
