Soil scientists use the capital letters O, A, B, C, and E to identify the master soil horizons<span>, and lowercase letters for distinctions of these horizons. Most soils have three major horizons: the surface horizon (A), the subsoil (B), and the substratum (C). Some soils have an organic horizon (O) on the surface, but such a horizon can also be buried. The master horizon, E, is used for subsurface horizons that have a significant loss of minerals (eluviation). Hard bedrock, which is not soil, uses the letter R.</span>
Answer:A. The release of calcium ions causes myosin and actin to attach to each other.
The contraction of skeletal muscles takes place by induction of a nerve impulse, which produces a movement and the interaction of the filaments containing proteins named as actin and myosin. This interaction of filaments is regulated by proteins called tropomyosin and troponin present on the actin filaments. The motor nerve causes the depolarization of the muscle membrane sarcolemma. This triggers the sarcoplasmic reticulum to release calcium ions. This calcium binds to troponin and thus allows the tropomyosine strand on the actin filament to displace so that the part of the actin where myosine head needs to be attached remain uncovered. Binding of the actin myosine filament results in contraction.
Hence, the release of calcium ions causes myosin and actin to attach to each other causes muscle contraction.
<span>The glacial sediment is known as glacial till.
Glacial till is derived from entrainment and erosion of material by the moving ice of the glacier.
It is being deposited a distance down -ice to form ground moraines, medical, lateral, and terminal. Glacial till is divided into primary deposits which are rewarded by fluvial transport.
The large rock which is transported by a glacier is called moraines. Moraines are formed from debris which is previously carried along by a glacier and consists of rounded particles which range in size from the large boulders.
Moraines are of different types, for example, ground moraines, lateral moraines, and recessional moraine.</span>
To conduct water and minerals to the leaves
