Tim is researching the regenerative property of stem cells as a possible method to treat neurological diseases. his research requires him to grow new nerve cells. which statement best explains why tim is using stem cells for this purpose? a. specific genes in a nerve cell’s dna can be activated to produce new stem cells. b. specific genes in a stem cell’s dna can be activated to produce new nerve cells. c. all genes in a nerve cell’s dna are activated, so new stem cells are produced each time the cell divides. d. all genes in a stem cell’s dna are activated, so new nerve cells are produced each time the cell divides.

D. All genes in a stem cell's DNA are activated.

The correct answer is option B.  Specific genes in a stem cell’s DNA can be activated to produce new nerve cells.

In order to produce nerve cells only specific genes are required to be activated not all the genes. Till the time an embryo is in 8 celled stage, all the cells of the embryo are totipotent i.e. each cell has the capability to reproduce/regenerate an entire individual. But, with advancement of time they get differentiated a bit and loose the capability to reproduce an entire individual and become restricted to reproduce only a few parts/organs of the body. Such cells which can reproduce only a specific organ/part of the body are known as pluripotent cells. In such differentiated pluripotent cells, only a few genes are activated. For example, the cells which are specified to form nerve cells will only have those genes activated which are required for forming nerve tissue and housekeeping genes. Other genes which are required to form other types of tissues like epithelial tissue, connective tissue and muscle tissue will not be active in the cells which are specified to form nerve tissue.

1. a host loses nutrients to a parasite

2. a parasite only benefits when the host is alive (cause if the host dies the parasite dies with it )

3. producers to consumers

4. the tapeworm is a parasite

5. they convert energy from the sun (photosynthesis)

6. sunflower-robin (i think im 80% sure)

7. producer

8. consumer

9. prey

10. fresh water snails ( cause the green algea is the producer and the snails are the primary consumers and the small fish consumer so is the big fish)