Answer:
Explanation:
infectious diseases can spread in a variety of ways: through the air, from direct or indirect contact with another person, soiled objects, skin or mucous membrane, saliva, urine, blood and body secretions, through sexual contact, and through contaminated food and water.
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Tumors are bunches of abnormal tissue growth, and they can constrict airways, and block your veins and arteries, causing them to be potentially fatal.
Answer:
Extra chromosomes can result in birth defects like down syndrome .
Explanation:
For the first question is that crabgrass because in the process of secondary succession a forest fire burns down a forest then grasses grow back, then annual flowers bloom and eventually trees begin to grow so crabgrass is the initial stages of secondary succession.