Because some species don't have a gender, therefore they have both make and female parts and are able to reproduce asexually.
I think.. heh.
Answer:
The alveolar walls and capillary walls share a membrane. That's how close they're getting. This allows oxygen and carbon dioxide to readily pass from the respiratory system to the circulation. Oxygen molecules bind to red blood cells as they return to the heart.
Answer:
Hypothesis, the amount of light must be enough to provide for the plant but not too much where it'll die and vice versa.
The amount of water should be enough that the plant can absorb it to sustain itself but too much or too little
Plant food in small quantities will help but too little or too much won't
Explanation: