Answer:
Gravity.
Explanation:
Without air, living organisms would suffocate and die.
Without water, living organisms would dehydrate and die.
Without energy, living organisms would die instantly.
Without space, living organisms would be squished together and die.
The only logical answer left is gravity.
Answer: Antigens
Explanation: The ABO system of blood grouping is based on the basis of the type of antigens that are present in the red blood cells. Erythrocytes is another name for the red blood cells. Antigens are molecules that are capable of eliciting immune response. There are two types of antigens: antigen A and B. Blood type A has only antigen A, blood type B has only antigen B, blood type AB has both antigen A and B while blood type O has no antigen (neither A nor B antigen).
Similarly, Rh trait is determined by the presence or absence of rhesus antigen in the erythrocytes. Rhesus antigen is an antigen first discovered in rhesus monkey. Rh+ indicates the presence of rhesus antigen in the red blood cells while Rh- indicates the absence of rhesus antigen in the red blood cells.
Answer:
Human microbiome
Explanation:
The microbiota that aggregates in the human tissues including placenta, skin, lungs, saliva, and seminal fluid is the human microbiome. The microbiota can be virus, bacteria, fungi and protists.
The microbiome present in the human gut helps in digestion and also provides immunity. Microbiomes can be healthy or unhealthy and an imbalance of both can lead to weight gain, high cholesterol and blood sugar. These are the ecological communities that includes symbiotic, commensal and pathogenic microorganisms.
