Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.

Fact 1: erosion causes a river to become deeper and wider. 
Fact 2: Erosion alters the constituents carried by water.
Deeper and wider rivers alter the constituents carried by water.

Fact 1: Oxygen is essential for cellular respiration for all aerobic organisms. 
Fact 2: Less oxygen for the mother means less oxygen for the baby.
Mothers need respiration for their babies.

Fact 1: Fission takes place when an animal divides into two parts. 
Fact 2: If the nucleus breaks up into lighter elements, it is called fission .

The nucleus breaks up into lighter elements when an animal divides into two parts.