The autonomic nervous system releases chemical messengers to influence its target organs
After the 1st half-life 250 g of the radioactive material will be left.
<span>After the 2nd half-life 125 g of the radioactive material will be left. </span>
<span>After the 3rd half-life 62.5 g of the radioactive material will be left. </span>
<span>Therefore after 60 minutes, 3 half lives would have occurred. </span>
<span>Therefore the half-life = 60 / 3 = 20 minutes when 250 grams of the original material would have remained radioactive. </span>
<span>Therefore the answer is A) About 250 gram of the material decayed in 20 minutes.</span>
Answer: Option D
All members of plants kingdom have multicellular embryos.
Explanation:
Kingdom plantae is the kingdom that includes all kind of plants, the seeds plant with and without flowers,green and brown algae, liverworts, mosses, ferns and so on. They all have multicellular embryos and they can undergo photosynthesids because of the presence of chloroplast.
This kingdom is divided into 5 divisions which are the peridophytes, bryophytes,thallophytes, gymnosperms and angiosperms. The bryophytes have life cycle of both sporophyte and gametophyte. Oogamus sexual reproduction is found in many protist of the order of algae and some bryophtes like fern and mossess. Egg cells surrounded by a jacket of sterile cells is found in Antheridia and bryophytes.
Answer: Hope this helps
GAS EXCHANGE: the intake of Oxygen and the expulsion of Carbon dioxide. In the capillaries of the alveoli, oxygen travels due to the concentration gradient into those capillaries. Carbon dioxide is then expelled from those capillaries.
RESPIRATORY MEDIUM: is air for animals and water for fish. It is basically the substance through with living animals receive their oxygen.
RESPIRATORY SURFACE: is where the gaseous exchange takes place. The oxygen and carbon dioxide move across the respiratory surface entirely by diffusion.