B is the correct answer Crossing over does not occur between genes
A variable that is not dependent, e.g. when inserting soap into water to test its surface tension, the independent is soap. It is the change that is controlled in the experiment.
In humans, the embryonic and the fetal forms of haemoglobin have a higher affinity for oxygen than that of adults this is because non-identical genes produce different versions of globin during development. So the correct option is A.
<h3>What is meant by oxygen affinity? </h3><h3> </h3>
The amount of oxygen delivered to the cells will depend on the haemoglobin's oxygen affinity.
Oxygen affinity is defined as the relationship between the saturation of haemoglobin oxygen, represented by SaO2 and the oxygen tension, represented by PaO2. This relationship is plotted by a dissociation curve which is S-shaped.
Thus, in the embryonic the fetal form, haemoglobin has a higher affinity for oxygen.
Therefore the correct option is A.
Read more about haemoglobin, here
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i) Because the worms would have either learned to become night worms or all day worms would have been eaten faster than they could reproduce
ii) Natural selection. Humans had no interaction with which worms survived, so it's all natural.
I hope this helps! Good luck!
Controlled population growth.
Explanation:
US is a highly developed country and it has expansive infrastructure and highly mechanized agricultural equipments. So first option is not a choice. Second, access to chemical fertilizers and pesticides in a country with such advanced agriculture infrastructure is very easy. Third US is well known for using GM crops.
US does not have a controlled population growth because if not the birth rate then migration of people to US is a major concern for that country. Thus, this will be a correct choice for the given question.