Answer:
Glossopteris and Lystrosaurus
Explanation:
Glossopteris is an ancient plant flora and Lystrosaurus is a fossil fauna, and both are found in many of the landmasses on earth. The Glossopteris flora appeared about 300 to 200 million years back and the Lystrosaurus appeared about 250 million years back on earth. They both existed from the time of late Permian to early Triassic age.
Both these fossils played an important role in understanding the continental drift theory or the plate tectonic theory. This evidence enabled geologists to understand how the continents have moved across the large ocean basin from one place to another and at what rate they are drifting currently. It helped in understanding how the super-continent Pangaea had broken into Laurasia and Gondwanaland, and further broken into the present location of the plates.
Answer:
Hemoglobin is responsible for binding and transporting oxygen in the body. It is a tetrameric protein that is found in high concentration in red blood cells (erythrocytes, red blood cells). Each hemoglobin molecule is made up of four subunits: two of the alpha type and two of the beta type, and each subunit can bind an oxygen molecule through its heme group.
Structure studies have shown that hemoglobin can adopt two conformations, called T (tense) and R (relaxed). Deoxyhemoglobin (in blue) is in state T, and the union of oxygen (in red) causes the transition to state R. The animation shows a close view of the heme group (in white, balls and rods) of one of the subunits of hemoglobin. In the deoxygenated state (T), the iron atom is not coplanar with the rest of the heme group due to its association with the histidine side chain. The union of oxygen displaces the iron atom so that it remains coplanar with the rest of the heme group, which in turn drags histidine, producing a larger-scale conformational change that affects the entire protein.
Hemoglobin can be considered as a tetramer formed by two alpha-beta dimers. The conformational change associated with the transition from T to R mainly affects the relative position of these two dimers (rather than the interactions between the alpha and beta subunits within a dimer). This is illustrated in the last stretch of the animation (drawn in black and white).
Answer:
what cnidarians you need to spell right
Skin serves as a protective barrier, a way to sense the world, and a layer that keeps nutrients and water inside the body. Four types of cells make up the skin, and they are produced mainly in the epidermis near the basement membrane.
