Explanation:
The statistical study of populations and how they change over time is called demography. Two important measures of a population are population size, the number of individuals, and population density, the number of individuals per unit area or volume.
Answer:
No 15N/15N labeled DNA was observed in second generation
Explanation:
Meselson and Stahl were doing an experiment to find out the semi-conservative mode of replication of DNA. The first cultured bacteria in 15N medium which was containing a heavy isotope of nitrogen. The DNA synthesized here had more density. After that they transferred the bacteria to the 14N containing medium. When bacteria reproduced and new strands of DNA were synthesized, they observed the following -
- The first generation had hybrid DNA with 15N/14N strands
- The second generation had both hybrid 15N/14N DNA and 14N/14N DNA strands
- There was no 15N/15N DNA observed.
In this way they proved that one strand of DNA is kept conserved during the replication.
Answer:
The correct answer is internal and external signals regulate the progression of the cell cycle at various critical check points.
Explanation:
The cyclic event that helps to prepare the cell for division is termed as cell cycle.Cell cycle are regulated by various internal and external factors which regulates the passage of cell through various critical check point.
For example Maturation promoting factor helps in the progression of frog egg oocytes cells from G2 to M phase.
G1 cyclin CDK helps in the passage of cell from G1 to S phase.
Answer:Without leaves green plants could not live.
Explanation:because from leaves a plant take breath or do respiration. In leaves of plants there are small pores or stomata from where they breathe. So if we can't breathe we can't live.so,Without leaves green plants could not live.