Answer:
There is a higher oxygen content in the air of the lungs than that of oxygen-depleted blood and a lower carbon dioxide concentration. This gradient of concentration causes gas exchange during respiration.
Explanation:
Answer:
d. xylem and phloem
Explanation: plants possess vascular bundles.these are bundles which includes xylem and phloem tissues and transport useful substances to various plant cells.
New Xylem and phloem are formed from the vascular cambium which divides into new cells .
Xylem and phloem are thin and slender with pipe-like structure.
The xylem transports water and dissolved nutrients to the cells where they are needed.
The phloem transports the product of photosynthesis (sugar) to parts what they are used up or stored .
Xylem cells are dead and consists in vessels,trachieds and xylem parenchyma.
Phloem cells are dead and consists in sieves cell, companion cells, phloem parenchyma and phloem fibres.
Answer:
The process which must occur when intending to work with research animals that are covered by the U.S federal regulations is ethical review and approval
Explanation:
Some animals had been threatened of extinction due to inconsiderate usage and killings due to either commercial, food, or research purpose. The U.S government, therefore, to prevent the extinction of such animals, formulated a law to restrict the engagement of these animals, even in research if the research will involve the slaughtering, injuring, or alter the physiological functions of the subject animals. Therefore, there has been needing to undergo a compulsory ethical review process when planning to undertake research. This process will objectively review the aims and objectives of the intended research, the methodology involved in achieving the aim, as stated in the research proposal. The importance of this review is to determine if the research will have deleterious effects on the animals, both spontaneously and in the future.
Answer:
Natural selection acts on <u>individuals </u>which may result in the evolution of <u>populations.</u>
Explanation:
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