The vertebral column, when seen from the side, has 4 curves: 2 convex curves (cervical and lumbar curves) and 2 concave (thoracic and sacral curves). This curves are the feature of the skeleton that allow a child to maintain balance in the upright position eventually.
When we are born we have a single concave curve throughout the whole vertebral column but, as we grow, still in the early months as we try to hold our head, the cervical curve starts to develop, and later, as we try to sit up, stand up, and walk, the lumbar curve aslo starts to develop. In few years we have all curves fully developed.
Carbon Dioxide (CO2) Water (H2O) and Sunlight
Answer:
This question is incomplete, the options are:
A) Decreased temperature
B) Strong southerly winds
C) Presence of a predator
D) Lack of water
The answer is C
Explanation:
A stimulus is something that provokes a response or reaction in a living organism. It can either be internal or external. An animal can respond to stimulus such as hunger, heat, predator etc.
However, among all the listed stimuli in the options, the PRESENCE OF A PREDATOR is most likely to result in a more rapid heartbeat in an animal. This is because the predator stimulus will require the animal to respond by running in order to survive. Running will increase its metabolic activity and cause its heartbeat to increase.
A gradient graph (derivative) representing the state of a dynamic equilibrium in a population should be a constantly straight (horizontal linear) line. Option 1 shows a increase which means it hasn't reached dynamic equilibrium. Option 2's average at all times is a constant number, which it fluctuates to maintain equilibrium. Option 3 shows a generally increasing trend, meaning the population is not balanced. Option 4 is plainly something that doesn't make sense as it is all over the place.
As the data points on Option 2 fluctuate around a certain value, it can be seen that Option 2 is the graph representing the state of a dynamic equilibium in the population.
Chameleons, those shade-shifting, intricately camouflaged lizards that can change color in response to environmental or behavioral influences. Since the oldest lineages of chameleons are all from Madagascar, scientists believe they evolved on the island and spread out from there. As far as paleontologists can tell, the first chameleons evolved shortly after the extinction of dinosaurs 65 million years ago. Unlike other animals that change color, such as the squid and octopus, chameleons do not modify their hues by accumulating or dispersing pigments within their skin cells, the researchers found. Instead, the lizards rely on structural changes that affect how light reflects off their skin, the researchers said. Although chameleons are believed to have originated in Africa or Madagascar, the oldest known fossil, 26 million years old, is Chamaeleo caroliquarti from western Bohemia.