Answer: https://www.wwf.org.uk/learn/wildlife/polar-bears#:~:text=Challenges%20affecting%20polar%20bears&text=The%20Arctic%20is%20warming%20about,ice%20to%20raise%20their%20young.
https://www.carbonbrief.org/polar-bears-and-climate-change-what-does-the-science-say
Explanation:
Answer: The Heart
Explanation:
The blood circulatory system (cardiovascular system) delivers nutrients and oxygen to all cells in the body. It consists of the heart and the blood vessels running through the entire body. The arteries carry blood away from the heart; the veins carry it back to the heart. The system of blood vessels resembles a tree: The “trunk” – the main artery (aorta) – branches into large arteries, which lead to smaller and smaller vessels. The smallest arteries end in a network of tiny vessels known as the capillary network.
There are two types of blood circulatory system in the human body, which are connected: The systemic circulation provides organs, tissues and cells with blood so that they get oxygen and other vital substances. The pulmonary circulation is where the fresh oxygen we breathe in enters the blood. At the same time, carbon dioxide is released from the blood.
Blood circulation starts when the heart relaxes between two heartbeats: The blood flows from both atria (the upper two chambers of the heart) into the ventricles (the lower two chambers), which then expand. The following phase is called the ejection period, which is when both ventricles pump the blood into the large arteries.
In the systemic circulation, the left ventricle pumps oxygen-rich blood into the main artery (aorta). The blood travels from the main artery to larger and smaller arteries and into the capillary network. There the blood drops off oxygen, nutrients and other important substances and picks up carbon dioxide and waste products. The blood, which is now low in oxygen, is collected in veins and travels to the right atrium and into the right ventricle.
This is where pulmonary circulation begins: The right ventricle pumps low-oxygen blood into the pulmonary artery, which branches off into smaller and smaller arteries and capillaries. The capillaries form a fine network around the pulmonary vesicles (grape-like air sacs at the end of the airways). This is where carbon dioxide is released from the blood into the air inside the pulmonary vesicles, and fresh oxygen enters the bloodstream. When we breathe out, carbon dioxide leaves our body. Oxygen-rich blood travels through the pulmonary veins and the left atrium into the left ventricle. The next heartbeat starts a new cycle of systemic circulation. Below is an attachment of a diagram that explains the connection between pulmonary and systemic circulation from google.
The answer is; C
Fossil fuels are the remains of an organism that lived in the past and have been preserved or their impression has been preserved. Fossils are studied to identify the difference (genetic and phenotypic) between past and future related organism and are carbon dated to determine the time in which the organisms existed. The study of fossils is called paleontology.
Answer:
Substitution
Explanation:
Mutations can simply be defined as change in the structure of a gene. Mutation can be of different types. These include, but not limited to:
- Insertion: This involves the insertion of extra base pairs into a DNA
- Deletion: Loss of DNA section
- Substitution: When a nucleotide base gets substituted with another base.
<em>Substitution of a base can lead to coding of different amino acid and hence, protein. It can also lead to coding of the same amino acid, otherwise known as silent mutation. Base substitution can also lead to the amino-acid-coding codon becoming a stop codon, leading to an incomplete protein.</em>
The correct answer is substitution.