Answer: arteries carry oxygenated blood away from the heart to the body. Veins carry oxygen-poor blood back from the body to the heart.
Answer:
Many evolutionary changes resulted in the transition of aquatic vertebrates into terrestrial organisms. Some of these are:
In terrestrial organisms, the respiratory system is more complex and enhanced than the aquatic vertebrates. For instance, the early amphibians had gills for respiration. But with the passage of time, lungs appeared which made life on land more feasible.
The formation of rigid and insulated body coverings also was an adaptation that emerged for making life feasible on land.
Limbs allowed movement on land. With the passage of time, feet developed from the limbs.
Answer:
Burning trash.
Explanation:
When we burn trash, it creates small particles of ashes. This small particle of ashes become mix up with the air. Air can blow these particles to the river or any other water resources, which contaminate the water and make a negative impact.
Raising livestock also has some negative impact on contaminated water and makes a negative impact, but burning trash makes the more negative effect more.
This is referred to as: spontaneous recovery
Spontaneous recovery is a theory of learning and memory which involves unexpected and recurrence of a conditioned response after a period of reduced response or delay. Spontaneous recovery is associated with classical conditioning and operant conditioning. Extinction will happen quickly after a spontaneous recovery, if the conditioned and unconditioned stimulus is not connected.
