QUESTION:Which of the following can typically decrease genetic variation?
toxins
predator-prey relationships
competition
new habitat
disasters
increased food supply
ANSWER:
1. toxins
2.predator- prey relationships
3.competition
4.new habitats
5. disasters
Answer:
From top to bottom, the vertebrae are:
Cervical spine: 7 vertebrae (C1–C7)
Thoracic spine: 12 vertebrae (T1–T12)
Lumbar spine: 5 vertebrae (L1–L5)
Sacrum: 5 (fused) vertebrae (S1–S5)
Coccyx: 4 (3–5) (fused) vertebrae (Tailbone)
Answer: Closed
Explanation:
At resting membrane potential( RMP) sodium channels remained shut, this is because , previously in depolarisation,the voltage gated sodium channels were opened for sodium to diffuse into the Axon. However these channels closed after reaching their refractory period,s.
Therefore a change in the extracellular concentration of sodium will not open them
Answer: etiolation of plant growth in shade, with fast growing cell without chloroplasts. Out of shade, cell differentiate again to produce photosynthesising cells
Explanation: It is a subjective decision as to what is ‘best’. Good examples are plant responses to changes in the nutrient supply.
when soil nitrogen is depleted some plants, such as legumes, grow nodules on their roots, with cells that release chemical signals to attract nitogen fixing bacteria.
Lack of light induces etiolation in many plants. New cells elongate and develop without chloroplasts, with rapid cell division exhibiting gravitropism, extending upward. When they grow beyond the shade area, cell differentiation changes again, to produce photosynthesising cells.
