What is deja vu?

deja-vuNearly two-thirds of all people experience deja vu at least once in a lifetime. Déjà vu is an apparent similarity of the current situation to something in the indefinite past. But despite its prevalence, surprisingly little data is gathered about the physiological nature of the déjà vu phenomenon. It’s complicated to gather information on deja vu because it’s hard to recall the details of a short experience that took place perhaps months and years ago. In addition, often a sense of deja vu dominates the other senses, reality seemingly doubles.

Déjà vu comes from French and literally means “already seen”. Earlier psychologists interpreted the phenomenon of deja vu as a disease, an illusion or hallucination of memory. Continue reading

Filed under Biology.

Why are plants green?

green leaf under microscope

Do you know why are plants green? Why leaves on trees are green? Plants as well as animals are alive. All living organisms need a source of energy to carry out biochemical reactions and a source of carbon to build their bodies. Animals (and humans as part of kingdom Animalia), fungi and most of bacteria obtain energy and carbon from organic compounds (i.e. consuming plants or other animals).
These organic compounds are produced only by cyanobacteria and plants in the process of photosynthesis. The term photosynthesis means literally “synthesis using light”: light energy drives the synthesis of glucose from carbon dioxide and water with the generation of oxygen. Energy and carbon stored in glucose can be used by other organisms in trophic chains. That’s why life on the Earth ultimately depends on plants. Continue reading

Filed under Biology, Chemistry.