Answer:
have curved protofilaments at their plus ends
Explanation:
Microtubules are polymers of tubulin proteins that function as the cytoskeleton of eukaryotic cells. Microtubules are dynamic structures that can grow and shrink at a rapid rate. During this process, tubulin subunits can associate and dissociate at the plus end of the protofilament. Tubulin subunits bind to two GTP molecules, one of which is hydrolyzed to GDP after assembly. When microtubules are unstable, protofilaments curl outwards because GDP-bound tubulin has a weak affinity (thereby curving it) and disassemble. The dynamic stability of microtubules is regulated by a feedback loop: when microtubules shrink, free tubulin concentration increases and microtubules start to grow. As microtubules grow, free tubulin concentration decreases and the rate of GTP-tubulin addition also decreases.
 
        
             
        
        
        
Answer:
C. Large herds of livestock release greenhouse gases
Explanation:
At every stage of production of food, food provisioning releases greenhouse gases into the atmosphere. Farming in particular releases significant amount of methane and nitrious oxide, two powerful greenhouse gases. Agriculture Baat contributes to climate change and is affected by climate change
 
        
             
        
        
        
Answer: A-T or G-C
Explanation: 
The single-nucleotide polymorphism in human genomes is a substitution of a single nucleotide which occur in a specific position at the genome. The A-T nucleotide may appear dominant in the most population, while the remaining minor population may have the G-C nucleotide. The DNA molecule in the population at this site have A-T or G-C.