A little trick i learnt: The atomic number reflects how many electrons there are, and there must be an equal charge. therefore, there are the same amount of protons as there are electrons. so if it has 81 protons, we look for number 81 in the periodic table, Thallium
        
             
        
        
        
Each daughter cell would still have 16 chromosomes
        
             
        
        
        
They are important because they contribute to clean air and water for 500 million people this is because they help sustain a healthy forest
        
             
        
        
        
Answer:
Carbon dioxide and oxygen are recycled through photosynthesis and cellular
respiration forever unless something interrupts.
Explanation:
Photosynthesis and cellular respiration are two distinct and opposite metabolical processes undergone by living cells. They are opposite processes because one utilizes the products of the other as reactants.
Photosynthesis is a unique process to autotrophic organisms like plants. It is the process whereby plants synthesize their food in form of organic molecules (glucose) by combining Carbondioxide (CO2) and water (H2O) in the presence of sunlight. 
The overall equation of photosynthesis is as follows:
6CO2 + 6H2O ------> C6H12O6+ 6O2
On the other hand, cellular respiration is the process whereby living cells obtain energy (ATP) by breaking down food molecules (glucose) using oxygen to produce carbondioxide (CO2) and water as products. The overall equation is:
C6H12O6 + 602 -----> 6CO2 + 6H2O
Based on the lab experiments, it can be concluded that Carbon dioxide and oxygen are recycled through photosynthesis and cellular
respiration because photosynthesis recycles/reuses the products of cellular respiration, which are C02 and H2O while cellular respiration recycles/reuses the products of photosynthesis, which are C6H12O6 and O2. This process occurs naturally in the environment and will continue to do so unless something interupts.
Option B is incorrect because light energy from the sun powers photosynthesis while option C is incorrect because photosynthesis transforms light energy to chemical energy while cellular respiration transforms chemical energy to thermal energy.
 
        
             
        
        
        
Answer:
Directional selection
Explanation:
Directional selection is a type of natural selection that favors one extreme phenotype of a genetic trait due to its survival and reproductive advantage to the individuals over another extreme phenotype and the intermediate phenotype. 
In the given example, the thick-leaved plants are better adapted to a drier climate due to reduced water loss. Directional selection favored the plants with thick leaves which in turn produced more progeny. Over the generations, the population evolved into the one having more number of thick-leaved plants.