Question 1 The world's population is spread very unevenly. Some spaces are empty or very sparsely populated: we speak of human deserts:
• Cold polar environments are the least populated regions: the ground, frozen permanently, prevents any form of agriculture, the very low temperatures make the habitat difficult.
• The hot or cold desert environments are also not busy: the lack of rain and the strong heat during the day limit the activities of men. The only exceptions are oases.
• The role of relief is more difficult to define. High temperate mountains like the Alps are generally sparsely populated but tropical chains like the Andes have a high population density. However, men have generally settled in the plains, in the valleys (along with the rivers) and on the coasts.
There are also other factors unrelated to land factors that influence population density such as job availability, or even historical factors.
Question 2: Birth rate:
The birth rate (sometimes called the crude birth rate) is the ratio of the annual number of births to the average total population for that year. When the population grows, the contact between people will be more permanent, and it will increase the marriage rate, and thus the birth rate. Age structure:The age structure is a mode of graphical representation of the structure (of age as well as of sex) of a population which constitutes a synthetic image of the past, present and future of the population.When a population resides for a long time in the same place (in favorable conditions, not raising the death rate and without moving), this will vary the age structure by observing an increase in the elderly population.
The movement of matter across a cell membrane against a concentration difference is called an Active Transport.
If the stimulus frequency is so high that the relaxation phase disappears completely, contractions become continuous in a process called complete tetanus.
What is tetanic contraction?
- When the motor neuron that innervates a skeletal muscle generates action potentials at an extremely rapid rate, a persistent muscular contraction known as a tetanic contraction is induced.
- A motor unit has experienced its motor neuron's maximum stimulation during this state, which lasts for a while. This happens when several impulses with a high enough frequency excite the motor unit of a muscle.
- Every trigger results in a twitch. A slow enough stimulus delivery will cause the muscular tension to release between each succeeding twitch. High frequency stimulation will cause the twitches to overlap, which will cause tetanic contraction.
Learn more about the Nervous system with the help of the following link:
brainly.com/question/3239081
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It is a low viscosity type of magma
Answer:
20% plus 20% is 40% of adennine and thymine. From 100% DNA bases subtract 40% and you will get 60%. Then divide this by 2 and you will get 30%. 30% of guanine and 30% of cytosine, because their amounts are equal in the DNA stand.
