Answer:
(B) resemble structures formed by bacterial communities that are found today in some shallow marine bays.
Explanation:
Extant stromatolites represent real "living fossils" for they are decendents of ancient forms that are associated with one of the first living forms on earth. Particularly, stromatolites are real bacteria communities where the autotrophic organism of the community are represented by cyanobacteria, which live along with heterotrophic bacteria. This clearly indicates that fossilized stromatolites points to bacteria (prokaryotes) as the first living things on earth (dated with not less than 3.5 billion year old)
Nowadays, stromatolites with cyanobacteria allows to reconstruct and understand fossilized forms. These current structures live in shallow marines ambients (e.g. Australia) but also in continental salt flats (e.g. Argentina) where few others bacteria can survive to these extreme conditions (high light exposure and salt concentration).
The cell membrane helps maintain homeostasis by controlling movement and what goes in or out of the cell.The cell membrane makes itself important by controlling the substances that penetrate the cell, either entering the cell, or leaving the cell<span>.</span>
Answer:
Carbohydrates, particularly glycoproteins act as ligands for cell surface receptors.
Explanation:
Glycoproteins
- Glyproteins are conjugate molecules comprising of carbohydrates conjugated with proteins.
- Glycoproteins play a vital role in cell-cell recognition, pathogen recognition and and cell adhesion.
- Glycoproteins on the surface of pathogens act as prominent antigens for the immune system.
Glycoproteins in Fertilization:
Several glycoproteins are attached to the surface of the zona pellucida, the envelope of the oocyte. In humans, these have been termed as ZP1-4.
Glycoprotein-sperm interaction is one of the most crucial steps in fertilization. This receptor-ligand interaction ensures the entry of the sperm into the zona pellucida, the extracellular coat, covered in glycoproteins that surrounds the oocyte or egg.
Carbohydrate binding proteins present on the surface of the sperm recognize the glycoproteins on the zona pellucida (ZP). This enables them to adhere to the surface of the ZP and also to gain access to the oocyte.
B- Electron transport chain
I believe it’s A Explanation, On average, hair tends to grow between 0.5 and 1.7 centimeters per month. That is about 0.2 to 0.7 inches. And I’m really sorry if I’m wrong but hope I helped
