Answer:
vitamin c
Cantaloupe.
Citrus fruits and juices, such as orange and grapefruit.
Kiwi fruit.
Mango.
Papaya.
Pineapple.
Strawberries, raspberries, blueberries, and cranberries.
Watermelon.
vitamin a
You can also get vitamin A by including good sources of beta-carotene in your diet, as the body can convert this into retinol. The main food sources of beta-carotene are: yellow, red and green (leafy) vegetables, such as spinach, carrots, sweet potatoes and red peppers. yellow fruit, such as mango, papaya and apricots.
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.
Because electrons are “pulled” towards the oxygen.
Robert Hooke observed the cells through a combination of lenses.
After Robert Hooke, the development of microscopy take place. After the development of the microscopy, scientist were able to observe the features of the cell. In order to formulate a cell theory observation of most of the cells was necessary. So, it was necessary to observe different types of cells from different organism. So, the advancement of the microscopy and observation process required for the formulation of the cell theory was the reason for the delayed development of the cell theory.
