C. The number of covalent bonds is equal to the number of unpaired valence electrons. For example, nitrogen and phosphorous both have 3 unpaired valence electrons thus forming 3 covalent bonds.
Answer: Option A
<u>Explanation:</u>
As temperature increases the rate of enzyme activity increases until it reaches approximately 37 degrees Celsius. As temperature increases beyond 37 degrees Celsius, the enzyme activity decreases. The activity decreases because the enzyme denatures.
Any enzyme has certain temperature, pH and pressure to maintain its activity. Only at the ideal or ambient parameters the enzyme works. Most of the enzymes that are present in the human body gets activated by 37 degrees and gets denatured beyond that temperature.
The thickness of the uterine lining becomes very thick when the level of the hormone progesterone reaches its highest levels. this makes sense based on the function of progesterone, as it is necessary for the implantation of the zygote.
Answer:
Mechanical barriers — which include the skin , mucous membranes , and fluids such as tears and urine — physically block pathogens from entering the body. Chemical barriers — such as enzymes in sweat , saliva , and semen — kill pathogens on body surfaces.
