This statement is true.
When a hormone binds to a hormone receptor it activates cell enzymes that start a cell cascade. This means that this enzyme makes changes in the activity other proteins or alters the expression of specific genes that change the cells activity.
Answer:
Haploid cells contain a single set of chromosomes. Gametes are an example of haploid cells produced as a result of meiosis. Examples of gametes are the male and female reproductive cells, the sperm and egg cell respectively.
Explanation:
Haploid describes a cell that contains a single set of chromosomes. The term haploid can also refer to the number of chromosomes in egg or sperm cells, which are also called gametes. In humans, gametes are haploid cells that contain 23 chromosomes, each of which a one of a chromosome pair that exists in diplod cells.
• Homologous structures: Both Ostriches have wings similar in form to those of their ancestors, but that do not allow the birds to fly.
Homologous structures are those that have structural similarities but are different in function. For example, if we look at the anatomical structure of a bird’s wing, it is very similar in structure with a human arm. However, over the course of time they have evolved to perform different functions.
• Vestigial structures: The inner ear bones of mammals have evolved from bones that form the jaws of reptiles.
Vestigiality refers to the process in which some structure lose their function over the course of evolution in some specie but they are functionally normal in other species. Such a structure is the inner ear bones of mammals which donot perform an important function in mammals but do perform in reptiles.
• DNA sequence data: Both Genes involved in RNA replication are conserved among bacteria and animals, suggesting a common evolutionary origin.
The sequencing of genetic data is an excellent method of finding the evolutionary histories and relatedness of different organisms. This field of sciences is called phylogenetics and the mentioned example is the result of phylogenetics.
• Analogous structures: The jointed legs of insects and vertebrates arose independently, indicating a different evolutionary origin.
Analogous structures are those that have similar function but they look very different in structure or anatomy. This is because they have been evolved from different ancestors and perform different functions. One example of these structures is mentioned, The jointed legs of insects and vertebrates that look different bur perform same function.
The answer is <span>Topoisomerase.
Topoisomerase is an enzyme responsible for twisting of DNA helix. After DNA strand is untwisted by helicase enzyme, DNA must be twisted again so the normal function of DNA can be sustained. If left untwisted, the replication fork will continue to grow, the normal function of DNA will stop.</span>
