He labeled the protein of bacteriophages with radioactive sulfur and their DNA with radioactive phosphorus. The bacteriophages were allowed to infect bacteria.
Correct answer:
"<span>B- homologous chromosomes join together to form tetrads during prophase I"
</span>It is during prophase I that homologous chromosomes join together (<span>synapsis)</span> and form tetrads - four chromatids are together in the new structure of two chromosomes - and this is the reason why crossing-over occurs in this phase. It is in this tetrad that both arms of both chromosomes may crossover and matching regions exchange places. This process results in homologous chromosomes recombination leading to genetic variability.
Based on the description of events, being that the lizard population appears to increase as soon as the snake population decreases, it appears that the snakes prey on the lizards. This suggests that the snake is a keystone species. A keystone species is one that has a dramatic effect on maintaining the balance of an ecosystem. As soon as the snake population decreases, major changes occur to the ecosystem, such as the lizard population increasing.
Therefore, the answer is D: <span>The snake is a keystone species in the ecosystem.</span>
Answer;
-Endocytosis
Explanation;
-Endocytosis includes; phagocytosis, pinocytosis, and receptor mediated: Endocytosis brings substances into the cell, plasma membrane surrounds the substances to be taken in, encloses them in a membrane-bound sac (vesicle) and brings them into the cell
-Phagocytosis: endocytosis of large solid particles (“cell eating”)
-Pinocytosis: endocytosis of extracellular fluid that contains dissolved solutes (“cell drinking”)
-Receptor-mediated: highly selective, ligands bind to specific receptor proteins on the plasma membrane and are then taken into the cell
-Exocytosis: the reverse of endocytosis: substances are removed from the cell; vesicles fuse with plasma membrane and release their contents into the extracellular fluid; important in nerve cells to release neurotransmitter and secretory cells to release cell products (ex. digestive enzymes, protein hormones).
