Francis Crick discovered the DNA structure.
They both have two types of DNA for twins
Answer:
D
Explanation:
An infection is when something invades your body, therefore, you are infected with micro-organisms making it D.
Answer: Possession of Valves
Explanation: Veins possess valves which ensures that blood flows in only one direction. Valves helps blood to flow back to the heart against gravitational force.
Arteries don't have valves because the pressure originating from the heart is capable of causing the blood to flow in one direction.
