The organism that transmits African sleeping sickness is the tsetse fly.
Answer:
Surfactant is a liquid produced by the alveoli in the lungs to keep the lungs from collapsing.
Explanation:
Surfactant is a fluid composed of lipids and proteins produced in the lungs that keeps the airways open and prevent the lung from collapsing. It is secreted by the alveolar epithelial type-II (AT-II) cells of the tiny air sacs found in the lungs called alveoli. It prevents the collapse of alveoli under the surface tension by reducing the surface tension at the interface between air and the aqueous fluid lining the alveolar surfaces. If enough surfactant is not present, the surface tension causes the tissue surrounding the alveoli to stick together after each exhalation and results in the collapse of alveoli.
Usually, in unborn babies, the production of surfactant starts at about 6 months of pregnancy and the surfactant helps the babies to breathe in the air immediately after delivery. But a premature baby can not produce enough surfactant and it results in the collapse of alveoli with each breath. The damaged alveolar cells collected in the airways affect breathing and the baby takes in less oxygen. This disorder is known as respiratory distress syndrome (RDS).
The level of carbon dioxide in the blood increases and results in acidosis which affects other organs in the body. Since the premature babies having RDS need extra oxygen and help with breathing, the treatment methods include providing extra oxygen through CPAP, placing a breathing tube into your baby's trachea, providing artificial surfactant and ventilator support.
Endosperm would be your best bet
Answer:
Option (d).
Explanation:
DNA is the genetic material of all the organism except some viruses. DNA is composed of nitrogenous base, deoxyribose pentose sugar and the phosphate group.
DNA replicatese by semi-conservative mode of replication in which one the daughter DNA consists of one newly synthesized strand and one parental strand. This mode of replication was explained by Messelson and Sthal experiment. The cells from 15N medium are transferred to 14N medium the band of intermediate density was observed. The daughter DNA consists of one 15N DNA strand and one 14N DNA strnd. This strand undergo replication in the 14N medium. This time one low density DNA band ( contains 14N - 14N DNA strand) and one intermediate density band ( 14N-15N DNA).
Thus, the correct answer is option (d).
The statement that is correct regarding the troposphere and the stratosphere is The ozone layer is in the stratosphere. The third one is true. The ozone layer acts as a protection layer that prevents UV light.
<h3>What are the layers of the atmosphere?</h3>
The atmosphere is divided into many layers, with the troposphere close to the earth and the thermosphere toward the sun, as shown in the diagram. in between two layers, such as the tropopause, which is present between the troposphere and the stratosphere. In the stratosphere, the ozone layer is present, which prevents the sun's UV rays from falling on the earth, and the troposphere is the region where the clouds are formed.
Hence, the correct answer is the third option, which is "The ozone layer is in the stratosphere."
Learn more about the atmosphere here.
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