Photoreceptor proteins are light-sensitive proteins involved in the sensing and response to light in a variety of organisms. Some examples are rhodopsin in the photoreceptor cells of the vertebrate retina,phytochrome in plants, and bacteriorhodopsin<span> and bacteriophytochromes in some bacteria.
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The standard plate count (SPC) method involves diluting 1.0m of bacterial culture into a series of water blanks, and then taking a sample from the water blanks to add to empty petri plates which will be filled with melted agar.
The standard plate count is a method used in microbiology, which is used to gain an insight to estimate the density of bacterial population which is present in a bacterial culture broth. This is done by plating a small concentration of the culture in a petri-dish and then counting the colonies which form in the petri-plate. This method is used mostly in the food industry, to find the density of mesophilic bacteria in food. This method is extremely essential to determine the primary source of the bacterial contaminant.
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20. The answer is 1 (Precambrian)
21. The answer is 4 (Pennsylvanian)
22. The answer is 2 (Bony Fishes, Dinosaurs, and Mammals)
23. The answer is 2 (Reptiles)
When tiny ice crystals in clouds stick together to form snowflakes, the result is snow. If enough crystals form a clump, they'll become heavy enough to fall to the ground. When temperatures are cold and moisture in the form of tiny ice crystals exists in the atmosphere, snow forms.
Answer:
The pressure differences on either side of the valve.
Explanation:
The heart valves open and close passively because of pressure differences on either side of the valve. When pressure is greater behind the valve, the leaflets are blown open and the blood flows through the valve. However, when pressure is greater in front of the valve, the leaflets snap shut and blood flow is stopped.
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