Answer:
12. In our somatic (body) cells, we have 2N chromosomes, but in our sex cells (sperm & eggs), we have half the number of chromosomes, which is N chromosomes
Explanation:
Carnoives eat meat and herbivores eat plants
Answer:
humans had more developed 'social' brains than Neanderthals, which enabled us to colonize new habitats and adapt to climate fluctuations
Explanation:
A more developed brain is considered to be an adaptive advantage that enabled early humans to leave Africa and colonize new habitats. Modern humans are able to adjust to new environments, situations, and socialize with other humans because the brain is a social organ. Although Neanderthals were able to occupy an important area of Europe, H. sapiens could colonize faraway lands, migrating into tropical forests, deserts, and glacial lands (colder areas than those colonized by Neanderthals). These early humans formed social groups which enabled them to find food more easily, thus greatly increasing their chances for survival.
Fossil fuel was non existent 2.5 billion years ago
Answer:
The animals present body structure is due to evolution. It is seen in each part including the structure of the heart. The vertebrate heart becomes complex from a simpler form.
Invertebrates, the heart of fishes is two-chambered having one auricle and one ventricle. The deoxygenated blood gets purified in the gills. They are aquatic and no lungs for breathing. The hearts pump a mixture of oxygenated and deoxygenated blood to the body.
The amphibians and reptiles have 3 chambered heart as they lead terrestrial mode of life. The gills modified into the lungs. The left auricle receives pure blood and the right auricle receives deoxygenated blood. The blood purified in the lungs and in the ventricle, both types of blood get a mix. The ventricle pumps the mixed-blood throughout the body.
In the case of birds and mammal, the heart is 4 chambered and the oxygenated and deoxygenated blood are separated. These two are higher vertebrates. No mix of pure and impure blood, the body receives only the oxygenated blood.
This shows to construct the phylogenetic tree of vertebrates - the fishes should be in the bottom, and above it amphibians, reptiles, then, mammals and birds on the top branch of the tree. As the chambers and structure of the hearts modified one after another.
