James gently releases a ball at the top of a slope, but does not push the ball. the ball rolls down the slope. which force caused the ball to move downhill?

The ball moved downhill due to the gravitational force.

When the ball is at the top of the downhill the gravitational force is more than the frictional force, this makes the ball come down without pushing it. Gravitational force is the universal force is applicable to all the objects on the earth. The force by which one object attracts other objects. Due to this gravitational force the ball rolls down to ground from downhill without any push.

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.

all answers true and false

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