Answer:
The correct answer is - option B. They are small because they lack a nucleus.
Explanation:
Red blood cells or erythrocytes are specialized cell that produce in bone marrow and have specific role such as carrying oxygen from lungs to deliver it to the various organs and carry out carbon dioxide.
In mammals these cells lack cell organelles such as nucleus and mitochondria, a major factor that determined its smaller size. The size of RBC are move through narrow vessels throughout a organism because of its specific size and shape that provide it space for hemoglobin and allow to be flexible and bend to move through narrow vessels.
Thus, the correct answer is : option B. They are small because they lack a nucleus.
The answer would be meteorites containing amino acids. Most of the amino the amino acids revealed in the new investigation were not guaranteed up in proteins or polymers. Furthermore, the most plentiful amino acids originate in biology are those that are set up in proteins, but such "proteinogenic" amino acids signify only a small fraction of the amino acids originate in the meteorites.
Answer:
The animals present body structure is due to evolution. It is seen in each part including the structure of the heart. The vertebrate heart becomes complex from a simpler form.
Invertebrates, the heart of fishes is two-chambered having one auricle and one ventricle. The deoxygenated blood gets purified in the gills. They are aquatic and no lungs for breathing. The hearts pump a mixture of oxygenated and deoxygenated blood to the body.
The amphibians and reptiles have 3 chambered heart as they lead terrestrial mode of life. The gills modified into the lungs. The left auricle receives pure blood and the right auricle receives deoxygenated blood. The blood purified in the lungs and in the ventricle, both types of blood get a mix. The ventricle pumps the mixed-blood throughout the body.
In the case of birds and mammal, the heart is 4 chambered and the oxygenated and deoxygenated blood are separated. These two are higher vertebrates. No mix of pure and impure blood, the body receives only the oxygenated blood.
This shows to construct the phylogenetic tree of vertebrates - the fishes should be in the bottom, and above it amphibians, reptiles, then, mammals and birds on the top branch of the tree. As the chambers and structure of the hearts modified one after another.
1. Gases are exchanged inside the
lungs through the surfaces of
thousands of alveoli to allow the
diffusion of carbon dioxide and
<span>oxygen
2. </span>Wastes are removed through the excretory system after passing through
either the kidneys urine or the digestive tract feces
3.Blood is redirected after a change in blood pressure after birth. Blood
now flows through the pulmonary artery to the lungs to receive oxygen
4. The lungs alveoli, the intestines, the
pulmonary artery, and the excretory system
hope it helps
