Answer:
If the petri plates are kept open for the longer duration of time then there are chances of cross contamination.
The contamination can be defined as growth of undesired microbes in the petri dishes or tubes which is no longer useful for the experiment.
The tube if kept open will develop the growth of contaminants in it. It can be cross contamination as well.
To avoid contamination the tubes and dishes should not be kept open for a longer duration of time.
Answer:
Water carries several physical properties such as chemical formula, appearance, boiling point, freezing point, density, viscosity and solvency.
An increase in temperature changes the density of water. When a water is heated or its temperature is allowed to increase it causes the water molecules to gain energy and move faster, which results in increase in water volume due to movement of water molecule far from each other. on the other side if temperature of water is decrease, it's molecules come closer to each other and decrease in the volume of water takes place.
Generally, the sun observes a solar cycle of eleven years. In this cycle, there are fluctuations in the activity, such as the ejected levels of solar radiation, and in the appearance of the sun, such as changes in the amount and size of sun spots, solar flares and other phenomena that occur on the sun's surface.
These changes also affect phenomena on earth, especially the auroras.
Pluto
Nasa's New Horizons mission made a close pass of Pluto this week. For more than 70 years, Pluto was one of nine planets recognised in our Solar System. But in 2006, it was relegated to the status of dwarf planet by the International Astronomical Union (IAU)
Answer: B) Are found in all the vascular plant groups
Explanation:
Megaphylls are found in vascular plant and they are leaf structures. They undergo photosynthesis and are gotten from the euphyllophyte structures. The have many large veins that branches apart.
microphylls and megaphylls are leaf structures that have diverse anatomical structures.
