<span>The spicules have an important purpose for loosely constructed animal such as sponge. First of all, spicules give structure which is vital due to loose construction. Secondly, it protects from predators. This is similar to porcupine quills in serving to protect.</span>
Rough ER<span> looks like sheets or disks of bumpy membranes while </span>smooth ER<span> looks more like tubes. </span>Rough ER<span> is called </span>rough<span> because it has ribosomes attached to its surface. The double membranes of </span>smooth<span> and </span>rough ER<span> form sacs called cisternae.</span>
One group of reptiles, characterized by the fossil Archaeopteryx, led to the evolution of birds. The correct answer is birds
Answer:
Magnesium, calcium, phosphorous, sulfur these are essential nutrients for plants. These are required in trace quantity but are very important for plant life. Point A. will be correct answer.
Explanation:
As in B. starch n cellulose are composed of only carbon, oxygen and hydrogen.
As in C. These elements are not required on special occasion but are necessary throughout plant life.
As in D. C H N O is the primary component plants need but these secondary nutrients are equally necessary for growth n structure of plant.
<u><em>So answer A. Is the correct option.</em></u>
Calcium plays the most important role in structure formation of plants. Also act as messenger molecule in signaling. Deficiency of calcium caused wilting , weakened stem and ultimately death of plant.
Magnesium is the key element in chlorophyll molecule. It is necessary for chlorophyll formation.
Sulfur is another very important element in plant life, it is necessary for protein synthesis in plants.
Phosphorous plays an important role in process of cell devision , photosynthesis and respiration.
Potassium is very crucial in gaseous exchange ,it operates the opening and closing of stomata.
Answer: Mitochondria and chloroplasts.
Explanation: Mitochondria create energy for both plant cells and animal cells through cellular respiration. Chloroplasts create energy for plant cells through photosynthesis.
