Answer:
The excretory system helps the respiratory system by removing carbon dioxide that is produced during respiration (third option).
Explanation:
The lungs are in charge of the breathing process, being the main organ of the respiratory system. Each lung is considered an excretory organ —belonging to the excretory system— since it is capable of eliminating the carbon dioxide (CO₂) produced by the metabolism during expiration.
As a result of the gaseous exchange, the oxygen entering the lungs through the inhaled air passes into the blood, while the CO₂ is removed from the blood. This CO₂ is removed during expiration, which makes the lungs part of the excretory system.
The other options are not correct because:
- <em>The excretory system does </em><u><em>not introduce more oxygen into the lungs</em></u><em>.
</em>
- <em>The </em><u><em>circulation of blood in and out of the lungs</em></u><em> is a function of the circulatory system.
</em>
- <u><em>Urine is not produced by breathing</em></u><em>.</em>
The outermost layer of the Earth is called the crust.
Answer: There are certain physical and internal aspects of living organism that is used for the classification of animals.
Explanation: The characteristics that define an organism to be classified as animal are:-
- Segmentation that defines the segments on the bodies of the animals which are of different kind
- Whether the animal is in the category of chordata or non-chordata
- Presence of embryo stage and number of tissue layers that are getting formed while the organism is developing
- There are most chances of sexual reproduction.
Lakes that have been acidified cannot support the same variety of life as healthy lakes. As a lake becomes more acidic, crayfish and clam populations are the first to disappear, then various types of fish. Many types of plankton-minute organisms that form the basis of the lake's food chain-are also affected. As fish stocks dwindle, so do populations of loons and other water birds that feed on them. The lakes, however, do not become totally dead. Some life forms actually benefit from the increased acidity. Lake-bottom plants and mosses, for instance, thrive in acid lakes. So do blackfly larvae.
