A fern is a vascular plant.
When you drop a ball, it is dropped DOWNWARDS so the number is represented by a negative number. If you toss the ball up it will be a positive number.
To answer your question:
When an object is dropped downwards there will be a negative number since the object is falling downwards.
The process that tend to reduceb the variety within a population is called B. Random fertilization.
The three major clades of bilaterian animals are the <span>ecdysozoa, lophotrochozoa, and deiterstomia.
Ecdysozoa are organisms that include insects, crustaceans, chelicerata, and myriapods. Lophoytochozoa include fossil organisms. Deiterstomia include chordata, echinodermata, and hemichordata.
Bilaterian animals have bilateral symmetry, meaning that they have a head, and a tail, as well as back and belly.
</span>
The Type O blood group is commonly called as universal donor because any blood group can receive the O blood group. The blood group O has no antigen. Due to the absence of antigen it doesn't agglutinate when come in contact with other blood groups in the plasma.
The agglutination reaction happens when opposite antigen and antibody reacts with each other. e.g.- Blood group A contains antigen A and antibody b and the blood group B contains antigen B and antibody a. Agglutination reaction occurs when the antigen A reacts with antibody a. As O blood group has no antigen, agglutination reaction doesn't occur.