A substrate is a reactant that is catalyzed by an enzyme.
B Nucleus
Only Eukaryotes have a nucleus. Prokaryotes have the DNA floating around in cytoplasm.
Answer:
Helper T cells are activated when they bind to their target antigen being displayed on an antigen-presenting cell. These cells then release what chemical? Cytokines, which is a chemical that signals B cells and other T cells to activate.
The different chromosomal combinations would be calculated using the formula;
2^n; where n is the number of different chromosomes. \
Using this formula ; when the diploid number is 14 (for 7 pairs ) will be given by; 2^7 = 128 different combinations.
It means that a barley plant which has seven pairs of chromosomes will have 128 different combinations.