Answer:
The correct statement concerning the cell membrane lipid molecules is that "energy is not expended during diffusion" (Option d)
Explanation:
Biological membranes are formed by two lipidic layers arranged with their hydrophilic polar heads facing the exterior and the interior of the cells, and their hydrophobic tails against each other. Membranes are fluid, which means that molecules that form it have the capability to move through it.
Lipids can easily change places with other neighbor lipids by <u>lateral diffusion</u> in the same layer. This is passive diffusion, which means that it does not need energy to happen.
Lipids can also diffuse transversally to the other layer, but this kind of movement is not as easy as lateral diffusion.
There are also other lipidic movements as rotational diffusion that imply the rotation of the molecule.
Through this lipidic bilayer, there is also a passive transport of some particles from one side of the cell to the other which happens because of concentration differences.
Answer:
1. optic disk 2. fovea centralis
Explanation:
Geothermal energy maybe is their answer choices
Answer:
All of the systems on Earth are classified as open systems. However, the Earth system as a whole is considered a closed system because there is a limit to how much matter is exchanged. Our Earth system has four spheres: the atmosphere, the biosphere, the hydrosphere, and the geosphere.
Explanation: The term “Earth system" refers to Earth´s interacting physical, chemical, and biological processes. The system consists of the land, oceans, atmosphere and poles. It includes the planet's natural cycles — the carbon, water, nitrogen, phosphorus, sulphur and other cycles — and deep Earth processes.
A system is a group of independent parts that work together as a whole. The Earth has four major systems or spheres. These systems are the geosphere, the hydrosphere, the atmosphere, and the biosphere.
The answer is (A). Hope this helps