Answer:
Higher
Explanation:
Molecules such as oxygen move from a higher concentration to a lower concentration across a semi-permeable membrane. This process is called simple diffusion.
Therefore, for oxygen to leave the alveoli and enter the blood, there would need to be a higher concentration of oxygen inside the alveoli and a lower concentration of oxygen in the blood. 
 
        
             
        
        
        
Answer:
Zebra mussels negatively impact ecosystems in many ways. They filter out algae that native species need for food and they attach to--and incapacitate--native mussels. Power plants must also spend millions of dollars removing zebra mussels from clogged water intakes.
Explanation:
 
        
             
        
        
        
1). A good example for mutualism is People and plants.  We provide plants Carbon dioxide.  Plants provide us Oxygen 
2).Biome is where you have your tundras, Rain forests, Deserts, etc.  then you have to give 3 characteristics like temperature, precipitation levels, soil type, etc.
I will have to get to question 3 later since im in class but ill give you the answer to that one.  its easy
        
             
        
        
        
Answer:
"Survival of the fittest" is a phrase that originated from Darwinian evolutionary theory as a way of describing the mechanism of natural selection. The biological concept of fitness is defined as reproductive success.
Explanation:
The Darwinian evolutionary theory was created by Charles Darwin.
Darwin published his theory of evolution with compelling evidence in his 1859 book On the Origin of Species, overcoming scientific rejection of earlier concepts of transmutation of species. By the 1870s, the scientific community and a majority of the educated public had accepted evolution as a fact.
 
        
             
        
        
        
 Answer: Spermatogenesis begins at birth and continues throughout a man's life.
The process in which
haploid spermatozoa develop from germ cells in the seminiferous tubules of the
testis is known as Spermatogenesis. Thus, the process of spermatogenesis start
with mitotic division of the stem cells that is located close to the basement
membrane of the tubules. However, a mature male gametes known as sperm but it
is commonly known as spermatozoa.