An asteroid impact with the Earth may have caused the K-T mass extinction. The atmosphere is the mixture of gases that surrounds the Earth. The Earth's atmosphere is mostly nitrogen. Everything is made up of tiny atoms. An atom is the smallest part of an element that has the properties of that element.
Autotrophs are the base of the food chain .
Auxins induce phototropism , apical dominance, cell elongation and many other reactions. The awn is a bristle-like extension of a plant near its tip. The axil of a plant is the angle between the upper side of the stem and a leaf , branch, or petiole . In flowering plants, the bud develop in the axil of a leaf. As stated in our privacy policy , we fully respect your privacy and will not use your e-mail address for any purpose other than the newsletter subscription.