If I eat candy then I will gain weight
If I shave my beard then it will grow back darker
With this you should be able to solve the rest :)
The four important characteristics of respiratory surface are:
1. Thin walls
2. Moisture
3. Large surface area
4. Blood supply
Respiratory system or respiratory tract is divided into upper and lower tract. Upper respiratory tract includes nose and its cavities, sinuses, pharynx and the part of the larynx. Lower respiratory tract consists of the trachea, bronchi, bronchioles and the alveoli.
Alveoli are the ends of the respiratory tract the smallest units in it. Alveoli are small folded air sacs that are branching off from alveolar ducts and providing an extremely large surface area for the gas exchange. Gas exchange occurs thanks to small blood vessels – capillaries that surround alveoli and it occurs via the process of diffusion.
So, respiratory surface is thin membrane also known as the blood–air barrier that consists of the alveolar epithelial cells, their basement membranes and the endothelial cells of the alveolar capillaries.
The first known single-celled organisms appeared on Earth about 3.5 billion years ago, roughly a billion years after Earth formed. More complex forms of life took longer to evolve, with the first multicellular animals not appearing until about 600 million years ago.
A unicellular or single celled organism is the term for organisms composed of only one cell.
I hope this helped!
Answer:
A. There are more people on transplantation lists than donor organs so xenotransplantation can save people’s lives
Explanation:
Xenotransplantation, ie using non human animal organs in transplantation, has following most crucial favouring argument
- Patients needing transplanted organs are much higher than people willing & able to donate them. So, there is extreme excess demand, needed to be satisfied for saving people's lives.
