The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
Answer:
The cell cycle is the replication and reproduction of cells, whether in eukaryotes or prokaryotes. It is important to organisms in different ways, but overall it allows them to survive. ... Plants require the cell cycle to grow and provide life for every other organism on earth.
pls give me brainless.
Answer:
The correct answer is - facilitated transport and secondary active transport.
Explanation:
GLUT transporter is a glucose transporter that helps in moving the glucose to its concentration gradient through the cell membrane. It is a transport protein that uses passive transport of facilitated transport that moves down their concentration gradient and therefore does not require chemical energy from ATP hydrolysis in the transport step.
Sodium-based GLUT or SGLT is also a glucose transport protein that exhibits secondary active transport as it develops electrochemical potential difference by moving ions out of the cell membrane, this gradient allows the movement of ions and molecules.
Answer: Cysteine residues are involved in disulfide bridges that helps to form tertiary structure in a protein
Explanation:
The tertiary structure of a protein will have a single polypeptide chain backbone with protein secondary structures. The interactions and bonds of the side chains within a protein determine its tertiary structure.
<u>The cysteine forms the disulfide bridges and they link the fragments within a polypeptide chain</u>. Sometimes those fragments are located very far from each other with respect to their primary structure. So, the tertiary structure is the three dimensional shape of a protein.
Answer:
4 steps of the scientific method are explained below
Explanation:
<u>1. Observation </u>
to observe and describe the natural process occurring
<u>2. Hypothesis </u>
formulate the phenomenon in a scientific or mathematical way
<u>3. experimentation ( testing of hypothesis)</u>
testing of hypothesis by performing experiments and analyzing the results of experimentation (if hypothesis is false go back to step 2
4. Theory establishment
based on the results of the third step by repeating the experiments to validate and verify, it will lead to formation of theory