HD is called an autosomal dominant disorder because only one copy of the defective gene, inherited from one parent, is necessary to produce the disease. The genetic defect responsible for HD is a small sequence of DNA on chromosome 4 in which several base pairs are repeated many, many times.
Carbon dioxide cannot pass through the protective waxy layer covering the leaf (cuticle), but it can enter the leaf through an opening (the stoma; plural = stomata; Greek for hole) flanked by two guard cells. Likewise, oxygen produced during photosynthesis can only pass out of the leaf through the opened stomata.
The Theory. Photosynthesis is the process in which light energy is converted into chemical energy. Using the energy of light, carbohydrates such as sugars are synthesised from carbon dioxide and water. The name photosynthesis is derived from the Greek words, photo for âlightâ and synthesis meaning âputting togetherâ.