Please answer!! What is the system protects the body against infections?
a
Circulatory system
Respiratory system
b
С
Immune system
d
Digestive system

The health, management and conservation of biodiversity, is a challenge facing ecosystems worldwide. the major factors that affect the health and function of the great barrier reef are climate change and pollution. which question investigates the effects of a biotic factor on the reef ecosystem?

Which of the following is the most likely outcome of global warming

Which line in the graph above best illustrates an effect of the carbon dioxide level in the blood on breathing rate before, during and after a period of exercise? 1.b,2.c,3.a,4.d