Synthesis of purine and pyrimidine bases in RNA and DNA
Here are the four postulates of natural selection, according to Charles Darwin:
1. variability - refers to different mutations that create different species
2. heritability - refers to the genes that are passed from one organism onto its descendants
3. overproduction of offspring - refers to the fact that more "children" is born than dies
4. natural selection - refers to those organisms that survive because they adapt to their surroundings better than those who will die
Explanation:
Los fósiles se forman a través de varios tipos de fosilización: mineralización, carbonización, momificación, y fundición y moldes. El proceso más común es el de mineralización, en el que los minerales de aguas subterráneas se filtran en las partes duras del organismo, como huesos y conchas, y los petrifican o los convierten en piedra.
Red platelets are too vast to leave any capillaries. As capillaries are just a single cell thick and have thin porous dividers this implies substances can diffuse out of them effortlessly. Helpful substances, for example, oxygen and sustenance diffuse out of the blood in the vessels into the tissue liquid where it is then taken to the cells.
Carrier proteins pick up specific molecules and take them through the cell membrane against the concentration gradient. Examples of active transport include: uptake of glucose by epithelial cells in the villi of the small intestine. uptake of ions from soil water by root hair cells in plants.
