I think its true because oxygen makes up about one-fifth of the Earth's atmosphere. Nearly 90 percent of the weight of the oceans is due to oxygen. In addition, oxygen is thought to be the third most abundant element in the universe and in the solar system
Developing Nations currently produce about 2600 kcal of food per person per day. The growth in food consumption around the world has been accompanied by a significant structural changes and a shift in the diet away from the staple foods such as roots and tubers towards more livestock products and vegetable oils.
The main significance of an eyespot in the cell of euglena is the detection or sensing of light and then orienting the organism away from or towards the light. Euglena is basically a genus of a single celled flagellate. I hope that this is the answer you were looking for and it has come to your help.
