Answer:
Temperatures gradient
Explanation:
There are distinct temperature gradient differences in the layers of atmosphere usually due to the main air molecule composition of the layers, the density of the molecules. The Troposphere the lowest layers is the densest and temperature decreases with increase in altitude. The stratosphere, on the other hand, has an increase in temperature with increase in altitude. Temperatures decrease with altitude in the mesosphere while the parameter increases with altitude in the thermosphere.
Answer:
The given statement is false.
A neuron is the basic structural and functional unit of the nervous system. It helps in transmitting information from one neuron to another neuron, gland, or muscle cell.
The conduction of nerve impulse is electrochemical in nature. It transmits the impulse electrically through the axon the nerve cells and chemically through synapses (gap between two nerves cells).
The axon terminals of pre-synaptic nerve cell release chemical messengers (also called neurotransmitters) in the synaptic cleft. These messengers then bind to the receptors present on the post-synaptic nerve cell and regenerate the nerve impulse.
Answer and Explanation:
The steps of the sliding filament theory are:
Muscle activation: breakdown of energy (ATP) by myosin.
Before contraction begins, myosin is only associated with a molecule of energy (ATP), which myosin breaks down into its component molecules (ADP + P) causing myosin to change shape.
Muscle contraction: cross-bridge formation
The shape change allows myosin to bind an adjacent actin, creating a cross-bridge.
Recharging: power (pulling) stroke
The cross-bridge formation causes myosin to release ADP+P, change shape, and to pull (slide) actin closer to the center of the myosin molecule.
Relaxaction: cross-bridge detachment
The completion of the pulling stroke further changes the shape of myosin. This allows myosin and ATP to bind, which causes myosin to release actin, destroying the cross-bridge. The cycle is now ready to begin again.
The repeated cycling through these steps generates force (i.e., step 2: cross-bridge formation) and changes in muscle length (i.e., step 3: power stroke), which are necessary to muscle contraction.
nebular hypothesis
The most widely accepted theory of planetary formation, known as the nebular hypothesis, maintains that 4.6 billion years ago, the Solar System formed from the gravitational collapse of a giant molecular cloud which was light years across. Several stars, including the Sun, formed within the collapsing cloud.
