Distribution of phenotypes within a population may be impacted by different types of natural selection. These types of selection include;
Directional selection involves a change in the environment shifts of phenotypes observed. Example is the giraffe neck-length, where the length got longer and longer over time to reach the leaves at the top of trees.
Stabilizing selection , this is a selection where an average phenotype is favored. example is number of eggs laid by birds such that too many eggs will be a waste of energy because some chicks would starve.
Disruptive selection is a selection where individuals with an average value of a trait are affected most while those with values below average are affected least. Example small individuals are capable of hiding from predators while big individuals can not fit in the hiding place but instead will fight with predators.
Answer:
Sweating is under the control of the sympathetic nervous system, which orchestrates the body's reaction to stressful situations and emergencies. The sympathetic nervous system activates the sweat glands through the chemical messenger acetylcholine.
Answer: d. The ecosystem reached its carrying capacity, and was not able to support continued population growth.
Explanation:
The carrying capacity can be defined as the maximum population size of the species that habitat or ecosystem can support or sustain on the basis of availability of food, water and other necessities. This is an important factor which keeps a balance of the population of a species in a particular region or ecosystem.
On the basis of the above information, The ecosystem reached its carrying capacity, and was not able to support continued population growth is the correct option to level off the rising populating of the birds.
Explanation:
Cancer occurs in dividing cells only because genetic materials divide into two equal portions during division. This process may be interrupted by carcinogenes or mutagenes to make mutate cells and then render them as cancer cells. In the brain, the cells are differentiated and there is no chance to start division, then how can cancer be found in the brain.
Answer:
D. Alveoli
Explanation:
Functionally, the respiratory system is separated into a conducting zone and respiratory zone:
Conducting zone consists of the nose, pharynx, larynx, trachea, bronchi, and bronchioles. These structures form a continuous passageway for air to move in and out of the lungs.
Respiratory zone is found deep inside the lungs and is made up of the respiratory bronchioles, alveolar ducts, and alveoli. These thin-walled structures allow inhaled oxygen (O2) to diffuse into the lung capillaries in exchange for carbon dioxide (CO2).
The respiratory zone begins where the terminal bronchioles join a respiratory bronchiole, the smallest type of bronchiole, which then leads to an alveolar duct, opening into a cluster of alveoli.
