Which signal are you talking about?
Answer:
D. There was a single transition from aquatic to terrestrial habitats
Explanation:
Based on the molecular differences at the level of DNA sequence and inheritance, the molecular phylogenies show that all land plants are a monophyletic group. This is why it suggests a single transition from aquatic to terrestrial habitats occur.
Answer:
The alveolar membrane- is where gas exchange between the blood and the atmosphere takes place. The gas molecules must diffuse across the alveolar epithelium and the capillary endothelium. ... Thus, the alveolar surface (as well as the respiratory bronchioles) have no cilia or mucus layer.
Explanation:
hope it helps =)
Answer:
Lymph nodes become swollen in response to illness, infection, or stress.
Explanation:
Swollen lymph nodes are one sign that your lymphatic system is working to rid your body of the responsible agents.
