Radially symmetric animals, such as hydras, are not found on land. However, bilaterally symmetrical animals live on land and in water. Propose a hypothesis to explain why radially symmetrical animals are best suited to aquatic life.

A hypothesis for the above-mentioned scenario can be generated as:

' As a majority of the animals in water have radial symmetry, then radial symmetry might be helping the animals to get more food.'

A hypothesis can be described as a tentative statement which can be either proved right or wrong with the help of experiments.

Radial symmetry means that the parts of the organism are arranged in a symmetrical pattern and the centre of the organism represents the main axis. This property will allow the organisms to uptake food from any direction and hence will make an organism adaptable to live in the aquatic environment.

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.