(1)
For unicellular organisms, cell division is important for the reproduction of the population, Unicellular organism mainly use cell division, also called binary fission, for pollution growth. This is because unicellular organisms are only composed of one cell.
Multicellular organisms use cell division for growth and reproduction. Cell division causes increase in the number of cells composing the organism hence its growth in size. Cell division is also used to create gametes that are used in reproduction by fertilization.
(2)
Even in fully developed organisms, cell division is important in tissue repair. In tissue homeostasis, there is a balanced rate of cell division and cell death . An example in muscles. Due to the stress experienced by muscle cells, they usually have a lower life span and therefore the damaged cells are often replaced with new ones by cell division. This prevents tissue wastage.
(3)
Growth factors signal the growth of a cell. They usually bind receptors on the cell surface and indicate how the cell should grow and divide base don environmental stimuli. An example is during regular exercises. Growth factors indicate that the muscle cells should divide regularly and grow bigger to accommodate the higher stress in the muscles from the workout. This is how your muscles grow bigger and stronger with more exercise.
(4)
Differentiation of cells occurs through the silencing of some gene allowing the cell to produce particular proteins (and other biomolecules) that align with its functions in the body. This especially critical in multicellular organisms. An example is that while al the cells in your body have the same DNA, some cells differentiate into liver cells while others into lungs, stomach, heart, and etcetera.
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For more on cell division check out;
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Answer:
The correct answer is B.
Explanation:
Option A is wrong. Mammals were not the prominent species before the extinction of dinosaurs because the mammal species that lived during the dinosaurs' era were so small that they only weighed several grams and occupied small areas as their habitats.
Option C is wrong. As dinosaurs became extinct, reptiles and "birds" remained as their descendant which evolved to some of the species that we know today.
Option D is wrong. Pangea started to break up to form the geographic isolation for the diversion of many species around 175 million years ago.
So the correct answer is B. Massive extinction disrupts and changes the food chain in such a big way that it triggers a domino effect that leads to species adapting to their new environment and diversifying thus forming new species in the process.
I hope this answer helps.
"Testes and Ovaries"
Two hormones are primarily responsible for pubic hair during puberty. Androgen and Estrogen, of which are spectively provided by the "Testes and Ovaries". Pubic hair is the bodies attempt of protecting those organs against friction with contact of skin.
<span>B- tree > insect > frog> snake> hawk
The food chains are represented by organisms interconnected by red arrows that point in the direction of the one that's eating. So, the relation that is explicit by the arrow is that the organism from where the arrow departs is eaten by the organism where the arrow is pointing towards to. So, the food chain that can be observed accurately in the food web is: the tree is eaten by the insect, the insect is eaten by the frog, the frog is eaten by the snake, and the snake is eaten by the hawk.
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