When lactose is not present, what happens to E. coli is that the genes that produce the enzymes needed to break down lactose are not expressed. The correct answer is B.
Answer:
The correct answer is "strengths: inexpensive, easy to culture, short life cycle, large number of offspring; weaknesses: invertebrate model, some diseases such as immunological cannot be modelled, anatomical features are very different from humans"
Explanation:
The fruit fly <em>Drosophila melanogaster</em> is one of the most used animal model for genetic and biomedical studies. There are many advantages of using Drosophila as model, including that it is very inexpensive to handle, it is easy to culture, it has a short life cycle allowing to observe the changes in phenotype very quickly and its large number of offspring allows to include several repetitions per trait in a study. However, there are some weaknesses of using Drosophila to study human biology. First, obviously the fruit fly is very different from humans, it is an invertebrate and its anatomical features are very different, which makes impossible to model some disorders such as immunological diseases.
The answer is B. Cnidarians
Cnidarian body has no left or right side, only tom and bottom surfaces. If you divide cnidarian a about central point, you will get equal parts. So, cnidarians are radially symmetrical animals. This group includes hydroids, jellyfish, anemones, and corals. In all groups, animals have stinging cells on tips of tentacles. They use them to capture the prey. Their name literally means stinging creatures.
Answer:
Pangenesis
Explanation:
The theory of 'pangenesis' was proposed by Darwin to explain the process of inheritance of genetic traits from one generation to next. According to this theory, gemmules are the tiny particles produced by all the somatic cells of the body of living beings. These gemmules are also called pangene. Blood carries gemmules from all the body cells to the gonads. These gemmules from all the somatic cells form germ cells in gonads.
