<span>The correct answer is option D.An ecosystem consists of a population of organisms and its physical environment, and a population is made up of many different communities of organisms. An ecosystem is a bilogical system of populations and environment. And a population consists many communities and finally the communities are nade up of organisms.</span>
Answer:
The embryo passes through multiple rounds of the cell cycle, but cytokinesis does not occur during M phases.
Explanation:
The cell cycle includes a series of events that make new cells from the existing cells. During the process, nuclear division during the M phase produces daughter nuclei. Nuclear division is followed by cytokinesis. Cytokinesis is the division of cytoplasm and results in the formation of daughter cells.
If a cell undergoing cell cycle forms daughter nuclei by mitosis, all the daughter nuclei are genetically identical. In the absence of cytokinesis, cytoplasm would not divide and the daughter nuclei will remain in the parent cell only. Repeated nuclear division without cytokinesis would produce multiple nuclei present in the parent cell.
Answer: C): the number of unpaired electrons.
Explanation: A covalent bond is a type of chemical bond formed by sharing equal number of electrons between two non-metal atoms so that both can attain the a stable octet or duplet structure of noble gases. The electrons shared by two non-metal atoms are the unpaired electrons. For example, in the formation of a chlorine molecule, a chlorine atom has seven valence electrons and electrons usually occur in pairs. Having seven valence electrons means that a chlorine atom has three pairs of electron and one unpaired electron in its outermost shell. The two chlorine atoms will combine together each donating its unpaired electron to be shared, thus leading the two atoms to attain stable octet structure of Argon.
