Answer :There was enough oxygen in the atmosphere to support a major burst of life on Earth
Explanation:
The Great Oxygen Event marks the time, approximately 2.5 billion years ago, when there was enough oxygen in the atmosphere to support a major burst of life on Earth
For the first half of the Earht's history, there was no oxygen in the atmosphere. It was inhabited only by single-celled organisms.Of those simple life forms, the cyanobacteria may have. evolved a way to take energy from sunlight, and used it to make sugars out of water and carbon dioxide. They used the same chemical process we know as photosynthesis. This released vast quantities of oxygen into the atmosphere and triggered the evolution of complex life.
Answer:
ubiquitin targets CDKs
Explanation:
Cyclins are named such because they undergo a constant cycle of synthesis and degradation during cell division. When cyclins are synthesized, they act as an activating protein and bind to Cdks forming a cyclin-Cdk complex. This complex then acts as a signal to the cell to pass to the next cell cycle phase.
Cyclins drive the events of the cell cycle by partnering with a family of enzymes called the cyclin-dependent kinases (Cdks). A lone Cdk is inactive, but the binding of a cyclin activates it, making it a functional enzyme and allowing it to modify target proteins.
Answer:
4 reasons here:
Explanation:
1) Adventure; boredom causes them to look for excitement, even if it's detrimental to their health.
2) Peer pressure;research shows that risk-taking among teens doubles when peers are around.
3) media;easy to guess, shows a lot of risky behaviour in glamorous or admirable ways.
4) Poor self-esteem; bullying can lead to poor self-esteem and higher chance of the victim becoming depressed and taking substance to cope with the depression, also leads to err, self-death
