Answer: Cardboard containers are best for protecting the riboflavin content of milk.
Riboflavin or vitamin B2 acts as a coenzyme in the metabolism of flavin mononucleotide and flavin adenine dinucleotide. The riboflavin is destroyed by irradiations and ultraviolet rays and therefore the milk is sold in opaque containers which are stable to heat. The tetra pack used now days is made up of cardboard and best suitable for using as a container to protect the riboflavin content of the milk.
I believe it is the sagittal plane
The substage condenser is either incorrectly positioned or the light stop is the wrong size for the objective- or there me be a smudge/mark on the eyepiece
Carbon is usually the result of burning fuels, cars, busses, taxi's
Cacti grow in the desert, which is a very hot climate. Not the best for both gaining and maintaining water supplies, due to the fact that water becomes vapour very quickly in conditions such as a desert (unless we're talking about polar deserts).
Keeping their stomata closed during the day stops water vapour from escaping their cells. While this does inhibit growth and stop new water molecules from entering, it allows the cactus to maintain a healthy amount of water within itself.