Answer: The correct answer is - 3) olfactory receptors neurons that detect smell. 4) photoreceptors neurons that detect light .
1) and 2) statements are correctly matched in the question..
Olfactory receptors are also called odorant receptors. The olfactory receptor neurons detect smell and thus give a sense of smell to the organism. They are present in the nasal cavity.
Photoreceptor neurons are those that detect light and they are present in the retina of eye.
Answer is c. If one essential nutrient within an ecosystem runs out, primary productivity will be limited
According to Vitousek et al., 2010, nutrient limitation defined as meaningful additions of an essential element in biologically available forms which increases the rate of primary productivity or increase in the biomass in an ecosystem. Alternately, nutrient limitation may also explained as when the supply of one essential nutrient of the ecosystem runs out the primary productivity of the plants will be limited.
Immigration and emigration is typically done with the purpose of looking forward to a better and more prosperous life, a more comfortable life where the money you earn can last you a pretty long time and buy you enough thing to live more comfortable than where you used to live. Therefore, when you move to a prosperous country, having children is not something you’ll worry about given to the commodities you’ll have and the easy access to baby food and baby clothes and stuff, therefore, when people emigrate/immigrate to more prosperous countries, they’re comfortable with the idea of having more children, and that leading to population growth.
All science involves observation.
