Its B, i had the same test
Answer:
C: A solid metal ball in the middle of a pool of liquid.
Explanation:
Since the student is studying the earth, the core area is made up of a solid metal ball in the middle of a pool of a liquid.
- The core is the inner most part of the earth.
- It exists in the middle of the earth.
- The core is divide into two layers; inner core and outer core.
- The inner core is a solid ball of metal.
- The outer core is a liquid metal under high temperature and pressure.
Answer:
c.reflects evolutionary history.
Explanation:
The best classification system in biology is that that reflects evolutionary history, this is because more developed animals evolved from ancestors, this means that little modifications on the DNA happened over the course of million of years that created the animals that we know today, so this little differences would be relfected on a classification system.
Stem cells arise from the inner mass of the cell
Signalling factors trigger differentiation in stem cells
Genes that lead to the production of undifferentiated blood cells are activated
Signalling factors cause undifferentiated blood cells to produce red blood cells
Explanation:
Red blood cells are formed in the bone marrow. The precursor to the RBC is stem cell which is undifferentiated and pluripotent. The stem cell gets differentiated to form immature RBCs. Immature RBC then gets divided and becomes mature. Stem cell giving rise to RBC is called Haemoctytoblast. The process of erythropoiesis takes 2 days to form new red blood cells
