1. Testing only one variable
A controlled variable means its the one that stays the same. In a controlled experiment, it means there is only one manipulated, (changed) variable.
Answer:
Option A, oxygen in the atmosphere
Explanation:
The highest level of oxygen reached during this phase of the geological cycle of earth. The oxygen level in Carboniferous period accounted for 35% as compared to 21% of oxygen in the atmosphere in present time.
Due to high oxygen content, the giant and wide varieties of terrestrial animal and plant species evolved. For example – size of insects and carwlies increased, plant became extremely giant, increase in number of tree ferns etc.
Hello there ^ _ ^
The correct answer is A
Genes and environment are both major influences.
Please trust my answer.
Answer:
e.) If exposure to cowpox gives immunity to smallpox in milkmaids, then milkmaids have a natural immunity and their blood should be used to develop a smallpox vaccine.
Explanation:
- Milkmaids who suffered from cowpox did not suffer from smallpox i.e. they were immune to the disease.
- If milkmaids did not suffer from smallpox then there must be some element of immunity that they received once they had recovered from cowpox, this would likely be found in their blood as antibodies.
Clay because it’s a mixture of dirt and runoff/water
