A.) Gymnosperms are the first seed plants.
        
                    
             
        
        
        
Hello there Jonnromeroo, thank you for asking a question here on Brainly!
You Asked ➤ Which of the following processes begins when a star enters the main sequence?
↴ OUR CHOICES ↴
A: Nuclear fission 
B: Nuclear fusion 
C: Condensation of a nebula
D: Appearance of a supernova
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Answer ➤ B: Nuclear fusion 
Explanation: When a star begins the process of being created, it is hot and dense. Really hot and dense! It begins to start fusing with helium which is the start of its main sequence called nuclear fusion. 
I hope this answer is helpful to you, but please let me know if you have any other questions regarding it.  
<em>- Qamar  </em>
 
        
                    
             
        
        
        
Some substances that were not initially filtered in the glomerulus, but must be eliminated from the blood, become a component of urine through the process of urine formation.
Urine: A liquid excrement consisting of water, salts, and urea, which is made in the kidneys then released through the urethra.
The process of urine formation involves 3 major steps:
- Filtration:- Blood enters the afferent arteriole during filtration, flowing into the glomerulus where filterable blood components—such as water and nitrogenous waste—move toward the interior of the glomerulus and nonfilterable blood components—such as cells and serum albumins—exit via the efferent arteriole.
-  Reabsorption: During this, ions and molecules will be returned to the bloodstream. As the fluid's osmolarity (ion concentration) fluctuates, water and ions are eliminated as it moves through the proximal/distal convoluted tubules, the loop of Henle, and the collecting duct.
- The process of secretion involves the removal of various substances from the blood into the collecting duct, including hydrogen ions, creatinine, and medications. Urine, the final result of all these procedures, is essentially a collection of chemicals that have not undergone tubular or glomerular reabsorption.
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Answer:
Primary active transport
Explanation:
Primary active transport is the transport in which molecules are moved against their gradient, with direct use of ATP as an energy source. Na/K pump  is an example  of primary active transport: Na ions are transported out of cell, K ions are moved into the cell. This pumps maintain concentrations of those ions and also creates voltage across the cell membrane, which can be used for the secondary active transport of other molecules (e.g. glucose).
 
        
                    
             
        
        
        
Answer:
gene
Explanation:
The basic unit of heredity that occupies a specific location on a chromosome is a gene.