A is the answer for this question
Answer:
The correct answer is D. Umbilical cord
Explanation:
The umbilical cord connects the fetus to the placenta and through it exchanges nutritional substances as well as oxygen-rich blood. The umbilical cord is maintained throughout gestation until the moment of birth, when it is cut and leaves a permanent scar, the navel. The umbilical cord is responsible for breathing and feeding the fetus until the moment it is born, so any failure or blockage in the circulation of oxygen and nutrients through the cord can lead to injury or even death of the embryo. It also serves to remove waste and carbon dioxide (CO2).
Answer:
Because fish are their own species.
The correct answer would be Fluoride was not used to help protect teeth then
Cavity is not a genetic disease and thus there is no relevance of gene transfer in this case. Thus option A, B and D gets ruled out.
However, flouride in a limited amount is very useful for removing the cavities. Flouride in the foood and water enters the blood stream and make the teeth strong from inside. While the Flouride in Saliva make the teeths stronger and cavity free from outside. It reduces reminization that causes the loss of minerals.
Thus lack of flouride makes the teeth more cavity prone.
Answer:
- It improves the growth of crops.
- It harms organisms that live in the oceans.
Explanation:
Fertilizers provide nutrients to plants, where the most needed nutrients in agriculture are nitrogen, phosphorus and potassium. Negative media coverage of the role of agriculture in pollution can make farmers feel guilty about the use of fertilizers. However, reducing fertilizer input can slow plant growth and exacerbate problems such as soil erosion. While it is important to be aware of the effects of fertilizers and use them with caution, it is also important for everyone to recognize that agricultural fertilizers are not the main source of pollution. If the plant uses all the nutrients and uses fertilizer wisely to prevent leaching, there is little chance of contamination.
Nitrate leaching from the soil poses a serious health risk and can contribute to soil acidification. When high levels of nitrogen are used, or when clover grass meadows fix significant nitrogen, nitrates inevitably seep out into groundwater where the water table is present, especially in sandy or well-drained soils. There is a possibility of entering. When this groundwater is used for domestic supply, leaching poses a serious health risk.
