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:
75years
Explanation:
Let the Father's age be represented by 2x
Let the Son's age be represented by x
Five years ago;
Man's age will be = 2x - 5
Son's age will be = x - 5
If the ratio of their ages five years ago was 9:4, then;
2x - 5/x-5 = 9/4
4(2x - 5) = 9(x - 5)
8x - 20 = 9x - 45
- Collect like terms
-20 + 45 = 9x - 8x
25 = x
Hence, the son's age = 25 years
If x = 25, the father's age (2x) will be 2 × 25 = 50years
The sum of their ages will be = 25years + 50years = 75years
Answer:
B
Explanation:
Water, sunlight and amount of oxygen in water
