The human sperm and eggs contain 23 chromosomes. The type of cell division that produces gametes with half the normal chromosome number is called meiosis. It is used to produce cells for repair and asexual reproduction. Gametes do contain different genetic information to each other and to the parent cell.
They are heterotrophic- not photosynthetic because they cannot perform photosynthesis
Answer:
It was an experiment to prove that DNA was made of genes. They discovered that protein was NOT genetic material.
Explanation:
"In their experiments, Hershey and Chase analyzed what happened when phages infect bacteria... They found that <em>when phages infect a host bacterium, the phages first attach themselves to the outside of the bacterium. Then, a piece of the phage enters the bacterium and subsequently replicates itself inside the cell. After many replications, the phage causes the bacterium to lyse, or burst, thereby killing the host bacteria.</em> Scientists classified the replicating piece as genetic material. Scientists also found that phages contained two classes of biological molecules: DNA and protein.
Hershey and Chase utilized a technique called radioactive isotope labeling. Chemical elements can exist in different structural forms called isotopes. Isotopes of the same element are nearly identical, but scientists can distinguish between them by experimental means. One way to differentiate between chemical elements with different isotopes is by analyzing their radiation. Some isotopes are less stable than others and give off radioactive signals that scientists can detect. Hershey and Chase marked phages by incorporating radioactive isotopes of phosphorus and sulfur in those phages. They allowed some phages to replicate by infecting bacteria, specifically Escherichia coli, or E. Coli, that scientists had grown in radioactive sulfur. The researchers let other phages infect and replicate in E. Coli that scientists had grown in radioactive phosphorus. DNA contains phosphorus, but not sulfur, whereas protein contains sulfur, but not phosphorus. Therefore, when Hershey and Chase marked phages with radioactive isotopes of those elements, they placed separate, distinguishable tags on the protein and DNA parts of the phages."
cited:
https://embryo.asu.edu/pages/hershey-chase-experiments-1952-alfred-hershey-and-martha-chase
Answer:
B.
Explanation:
The movement of substances(ions and molecules) against their concentration gradient is called Active transport.Since these substances are moving against whew they are already in abundance,extra energy is needed for them to move against this gradient.Therefore,ATP.,oxygen is needed by the cells undergoing this transport process to transfer substances into the cells.
It is useful for entry of substances in plants e.g glucose,and for transport of materials in intestine in man
Na-K pumps, exocytosis,endocytosis are examples of this transport process.
It is inhibited by lack of oxygen,cyanide etc.
