Neurotransmitters are the chemical molecules, which help in transfer of the signals from one neuron to another. Inside the neurons, the signals are transferred as electrical signals, but at junction of two neuron, which is known as synapse, the signals are transferred in chemical forms.
These neurotransmitters have a definite shape and are recognized by the receptors present in the receptor site of the succeeding neuron. The neurotransmitters from the synapse binds to the receptor site of the receiving neuron. binding of the neurotransmitter to the receptor causes excitation of the receiving neuron, which also known as postsynaptic neuron.
Hence, Like a key in a lock, the shape of the neurotransmitter must bind with the receptors of the receiving neuron.
There are many internal factors which living organisms respond to, two of them are temperature and hormone levels. Organisms respond to internal factors in order to stay healthy and survive. The internal environment of living organisms has to be kept relatively constant, this is constancy is achieved through the process of homeostasis.
Answer:
1. Stabilizing Selection
2. Directional Selection
3. Disruptive Selection
Explanation:
Stabilizing Selection
This type of natural selection occurs when there are selective pressures working against two extremes of a trait and therefore the intermediate or “middle” trait is selected for. If we look at a distribution of traits in the population, it is noticeable that a standard distribution is followed:
Example: For a plant, the plants that are very tall are exposed to more wind and are at risk of being blown over. The plants that are very short fail to get enough sunlight to prosper. Therefore, the plants that are a middle height between the two get both enough sunlight and protection from the wind.
Directional Selection
This type of natural selection occurs when selective pressures are working in favour of one extreme of a trait. Therefore when looking at a distribution of traits in a population, a graph tends to lean more to one side:
Example: Giraffes with the longest necks are able to reach more leaves to each. Selective pressures will work in the advantage of the longer neck giraffes and therefore the distribution of the trait within the population will shift towards the longer neck trait.
Disruptive Selection
This type of natural selection occurs when selective pressures are working in favour of the two extremes and against the intermediate trait. This type of selection is not as common. When looking at a trait distribution, there are two higher peaks on both ends with a minimum in the middle as such:
Example: An area that has black, white and grey bunnies contains both black and white rocks. Both the traits for white and black will be favored by natural selection since they both prove useful for camouflage. The intermediate trait of grey does not prove as useful and therefore selective pressures act against the trait.
Answer:
Do Nitrogen, Phosphorus, and Potassium Fertilizers Do for Plants? Nitrogen in Fertilizer. In simple terms, nitrogen promotes plant growth. It is associated with leafy, vegetative growth. Phosphorus in Fertilizer. Phosphorus is involved in the metabolic processes responsible for transferring Each of these fundamental nutrients plays a key role in plant nutrition. Nitrogen is considered to be the most important nutrient, and plants absorb more nitrogen than any other element. Nitrogen is essential to in making sure plants are healthy as they develop and nutritious to eat after they’re harvested. Soil is a major source of nutrients needed by plants for growth. The three main nutrients are nitrogen (N), phosphorus (P) and potassium (K). Together they make up the trio known as NPK. Other important nutrients are calcium, magnesium and sulfur.
Explanation: hope im right
Answer: We have found fossils that share specific bony traits that are found only in all whales but absent in every other mammal group, indicating descent from a shared common ancestor with modern whales, and these fossils had legs fully adapted for walking on land, and fundamentally identical to those of older mammals that precede the shared common ancestor that these mammals share with whales.
This tells us that the shared common ancestor of whales and these mammals with legs almost certainly had legs themselves, and inherited those legs from their own older mammal ancestors.
Therefore, whales have ancestors in their lineage that walked on land with legs.
(We also have multiple fossils of ancient whales that had legs transitional in form between fully terrestrial walking legs and flippers adapted for swimming, and modern whales still possess a remnant hip bone buried deep in their bodies.)
