Answer:D
Explanation: The pulmonary air sacs of birds only permit a unidirectional flow of air through the lungs. Unidirectional flow means that air is inhale and exhale through one trachea alternatively. This means the bird lungs only receive largely fresh air which has a high oxygen content during inhalation and do not receive fresh during exhalation. While air flow bidirectional in mammals.
Hello! THere are many differences between a grassland and a savanna. For one, a savanna is a grassland, however, A savanna is usually very dry. A savanna also has very few trees, while grasslands can be plush with many trees. Grasslands could also be in mountains while savannas are vast dryer lands with animals who live in dry weather. Grasslands also contain a lot of water sources like lakes, rivers, ponds, and savannas usually don't. Those are just a few o the many differences between them!
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Answer:
DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C). The order of these bases is what determines DNA's instructions, or genetic code.
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Answer:
Food chain Desert or Forest , producer, Primary consumer,Secondary Consumer, Tertiary Consumer, decomposer
Explanation:
