Answer:
b. a semi-permeable double layer of phospholipids that have hydrophilic heads and hydrophobic tails
Explanation:
B is correct as the cell membrane is selectively semi-permeable. It is selectively semi-permeable because this quality allows it to control what can and can't enter the cell, and how it does so.
The cell membrane also has a phospholipid bi-layer comprised of a double layer of phospholipids which have hydrophilic head and hydrophobic tails. This is because the heads are made of phosphate and are polar and are therefore attracted to water (hydrophilic), while the tails are made of lipids (i.e. fats, oils) which do not mix with water and are therefore hydrophobic.
The properties of each phospholipid is also why they form the double layer structure, the hydrophilic heads naturally face outwards into the water and protect the hydrophobic tails on the inside.
Hope this helped!
Answer:
1st is correct
Explanation:
At its simplest, a dog's digestive system is a long tunnel that runs from their mouth to the anus. Food goes in at the mouth and travels through this tube and at various stages is broken down and either absorbed into the body or excreted as waste at the anus.
Ancient organism remains, fossil layers, similarities among organisms alive today, similarities in DNA and similarities of embryos.
Answer: Option A.
Polar ice cap in Antarctica.
Explanation:
Scientist drill ice cores from inside the polar ice cap in Antarctica to study variability of climate and differentiate that variability From global climate change. Each layer of the ice tells about weather and what the Earth was like when the first snow fell.
For example, Le grande says that as snow deposits into a growing glacier, the temperature of the air imprints on water molecules.
Icy layers hold particles,aerosols, sea salts, trace elements that were in the atmosphere before and they abide for thousands of years and provide evidence of past events.
