D. Fossil fuels are the remnants of organisms that lived a long time ago and were buried, heated, and formed into hydrocarbons.
Answer:
#2 is B #3 is
Explanation:
Plant cells have cell walls around them, and animal cells don't have cell walls. The cell walls give plant cells their boxy shapes. That's nice for plants, because it gives them the ability to grow up and out, where they can get lots of sunlight for making their food.
The nucleus maintains the integrity of genes and controls the activities of the cell by regulating gene expression- the nucleus is, therefore, the control center of the cell.
Answer:
Cyanobacteria are microscopic organisms found in all kinds of water. They are single-celled organisms and produce their own food from sunlight via photosynthesis. Cyanobacteria are important to evolution because they developed the oxygen atmosphere we live in by producing waste from cyanobacteria. Plants also evolved from Cyanobacteria.
Simply put, a genetic mutation comes from a change in the DNA; this change can result from an extrachromosomal element, an alteration of the inherited nucleotide...
The basic building block of nucleic acids, such as DNA and RNA. It is an organic compound made up of nitrogenous, a sugar, and a phosphate group (http://www.biology-online.org/dictionary/Nucleotide)
Answer:
"As a molecule moves through the plasma membrane it passes through <em>a hydrophilic layer of phospholipid heads then a hydrophobic layer of phospholipid tails and then another hydrophilic layer of phospholipid heads".</em>
Explanation:
Biological membranes are formed by two lipidic layers, proteins, and glucans.
Lipids characterize for being amphipathic molecules, which means that they have both a hydrophilic portion and a hydrophobic portion at the same time. These molecules have a lipidic head that corresponds to a negatively charged phosphate group, which is the polar and hydrophilic portion. They also have two lipidic tails that correspond to the hydrocarbon chains -the apolar and hydrophobic portion- of the fatty acids that esterify glycerol.
Membrane lipids are arranged with their hydrophilic polar heads facing the exterior and the interior of the cells, while their hydrophobic tails are against each other, constituting the internal part of the membrane.
Through this lipidic bilayer, some molecules can move from one side of the cell to the other, which happens because of concentration differences. When this occurs, molecules must pass through the hydrophilic layer of phospholipid heads then through the hydrophobic layer of phospholipid tails and then again through another hydrophilic layer of phospholipid heads.
