Cell membranes serve as barriers and gatekeepers. They are semi-permeable, which means that some molecules can diffuse across the lipid bilayer but others cannot.
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:
Robinson explains how she uses layers in fossilized corals to understand what the environment was like overtime. By finding out what mainly makes up each layer and finding out roughly how old each layer is, she can begin to understand what the chemical composition and climate was like when the coral pieces were alive
answer is C- lesson 4 page 11: The Dermal tissue contains the epidermis as well as root hairs.
When something is cooled, its atoms compact and become more dense. vice versa for heating
