The ovary of a flower in a plant is where it produces seeds and develops fruits
D. Photosynthesis only takes place in the light, while cellular respiration takes place in the light and dark.
Answer:
Advanced forms of life existed on earth at least 3.55 billion years ago. In rocks of that age, fossilized imprints have been found of bacteria that look uncannily like cyanobacteria, the most highly evolved photosynthetic organisms present in the world today. Carbon deposits enriched in the lighter carbon-12 isotope over the heavier carbon-13 isotope-a sign of biological carbon assimilation-attest to an even older age. On the other hand, it is believed that our young planet, still in the throes of volcanic eruptions and battered by falling comets and asteroids, remained inhospitable to life for about half a billion years after its birth, together with the rest of the solar system, some 4.55 billion years ago. This leaves a window of perhaps 200-300 million years for the appearance of life on earth.
divine interventionThis duration was once considered too short for the emergence of something as complex as a living cell. Hence suggestions were made that germs of life may have come to earth from outer space with cometary dust or even, as proposed by Francis Crick of DNA double-helix fame, on a spaceship sent out by some distant civilization. No evidence in support of these proposals has yet been obtained. Meanwhile the reason for making them has largely disappeared. It is now generally agreed that if life arose spontaneously by natural processes-a necessary assumption if we wish to remain within the realm of science-it must have arisen fairly quickly, more in a matter of millennia or centuries, perhaps even less, than in millions of years. Even if life came from elsewhere, we would still have to account for its first development. Thus we might as well assume that life started on earth.
How this momentous event happened is still highly conjectural, though no longer purely speculative. The clues come from the earth, from outer space, from laboratory experiments, and, especially, from life itself. The history of life on earth is written in the cells and molecules of existing organisms. Thanks to the advances of cell biology, biochemistry and molecular biology, scientists are becoming increasingly adept at reading the text.
An important rule in this exercise is to reconstruct the earliest events in life's history without assuming they proceeded with the benefit of foresight. Every step must be accounted for in terms of antecedent and concomitant events. Each must stand on its own and cannot be viewed as a preparation for things to come. Any hint of teleology must be avoided.
Answer:
Of the 23 pairs of chromosomes in any normal human cell, the first 22 pairs provide directions for an individual's body and brain development. Scientists now estimate that about half of a person's personality traits and cognitive abilities can be traced to genetic influence and that psychological disorders arise from the interactions of many genes.
Explanation:
Chromosomes are small molecules that have the ability to carry all the genetic information needed to form a living being. These chromosomes are donated by an individual's parents and are used to form 23 pairs that determine all the internal and external characteristics of an organism. Among these 23 pairs, one pair will be responsible for determining the individual's gender, and the other 22 pairs will be responsible for the instructions that will make up the entire body and brain of the individual. Many scientists believe that chromosomes are responsible for even a part of a person's personality traits and that the genes they carry are directly related to the existence of psychological disorders.
