Answer:
<u>d. Transport proteins within the membrane serve as a tunnel for molecules to enter the cell.
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Explanation:
Solutes are typically moved across the cell through either passive or active transport. The cells, surrounded by a bilipid layer or plasma membrane is amphiphlic- its polar, hydrophilic lipid heads face outwards, while their non-polar hydrophobic lipid tails face inwards towards each other.
While lipid-soluble molecules move across the layer easily, it is also difficult for charged and also large molecules to move across its surface, into the cell. Transmembrane channels, <u>embedded within the membrane</u>, help to maintain selective permeability as transport proteins, pores and gated channels. Simple diffusion happens as a method of passive transport in cells through plasma membranes.
The solutes travel through the plasma membrane in the process of diffusion from regions of high concentration to regions of low concentration; this occurs without the use of energy. <u>Molecules moving against their concentration require active transport mechanism to cross the membrane</u>.
Answer:
<em>This is an example of natural selection (adaptation).</em>
Explanation:
Natural selection tends to favor those organisms which are better adapted to live in an environment.
As tortoises having flat shell and long neck were better adapted to live in barren area, hence through natural selection those organisms were favored in such an ecosystem.
As tortoises that lived on the vegetative lands were more adapted to live in such an ecosystem, hence through natural ecosystem these organisms were favored and increased in numbers.
Answer: Anxiety disorder
Explanation:Anxiety disorders are a group of mental disorders characterized by significant feelings of anxiety and fear.Anxiety is a worry about future events, and fear is a reaction to current events.These feelings may cause physical symptoms, such as a fast heart rate and shakiness
<span>If a person has type B blood, only anti-A antibodies are present in his or her blood.</span>
THE ANSWER IS: <u><em>Make a model</em></u>
Different scientific questions and hypotheses require different types of scientific investigations. Some questions can be answered through controlled experiments. Other questions can be answered through collecting specimens, building models, and/or making observations.
For example, questions about events that occur over thousands of years are best studied through models.
