The correct answer is c. smoke stacks.
Smoke stacks are chimneys or funnel shaped structures which emit smoke from a factory, vehicles and industrial set ups. Smoke stacks mostly discharge carbon dioxide and water vapor and oxides of nitrogen into the atmosphere. The exhaust released from smoke stacks cause air pollution. Air pollution can cause ailments like asthma and cancer. Thus, smoke stacks are not a source of water pollution.
Answer:
The relationship data of the dominance for each trait between the alleles was available with Mendel. The purpose of the dihybrid cross was to determine the type of relationship that existed between the pair of alleles.
Answer:
The testes are two oval-shaped male reproductive glands that produce sperm and the hormone testosterone.
The controlled experiments are performed by the scientists, when they want to study the changes in the sample on changing a single variable. So, the correct answer is option (b).
In case, all variables are kept same, no changes would be observed in the experiment sample. A controlled experiment can be performed on living thing as well as non living. But, controlled experiment cannot be performed on the things which are influenced by a lot of variables, as they cannot create realistic results. So, the option (a), (c), and (d) are incorrect.
