⁣In single circulation, blood flows to and from the heart through a single pathway, whereas in double circulation there are two separate pathways that are connected to the heart through which oxygenated and deoxygenated blood flows.

⁣The central nervous system (CNS) is made up of the brain and spinal cord. It is one of 2 parts of the nervous system. The other part is the peripheral nervous system, which consists of nerves that connect the brain and spinal cord to the rest of the body. The central nervous system is the body's processing centre.

⁣Health, as defined by the World Health Organisation, is a state of mental, social as well as physical being. Disease being the opposite, is a hindrance in the well being of our body that affects the functioning of organs and organ systems.

⁣Plant cells have a cell wall in addition to a cell membrane, whereas animal cells have only a cell membrane. Plants use cell walls to provide structure to the plant. Plant cells contain organelles called chloroplasts, while animal cells do not.

⁣At each cell in your body, oxygen is exchanged for a waste gas called carbon dioxide. Your bloodstream then carries this waste gas back to the lungs where it is removed from the bloodstream and then exhaled. Your lungs and respiratory system automatically perform this vital process, called gas exchange.

⁣Genetic variations that alter gene activity or protein function can introduce different traits in an organism. If a trait is advantageous and helps the individual survive and reproduce, the genetic variation is more likely to be p****ed to the next generation (a process known as natural selection).

⁣Stomata are generally more numerous on the underside of leaves. They provide for the exchange of gases between the outside air and the branched system of interconnecting air canals within the leaf. A stomate opens and closes in response to the internal pressure of two sausage-shaped guard cells that surround it.

Excretory system
The excretory system removes waste and toxins from the human body.
Your skin eliminates waste by sweating.
Your lungs eliminate carbon dioxide.
Your kidneys filter over 180 liters of blood in order to produce urine.
The kidneys filter waste like urea. This liquid that is collected is called urine.
Your kidneys are made up of millions of filtering units called nephrons.

⁣Every person has a blood type, (O, A, B, or AB) and an Rh factor, either positive or negative. The blood type and the Rh factor simply mean that a person's blood has certain specific characteristics. The blood type is found as proteins on red blood cells and in body fluids. The Rh factor is a protein that is found on the covering of the red blood cells. If the Rh factor protein is present on the cells, the person is Rh-positive. If there is no Rh factor protein, the person is Rh- negative.
The following are the possible combinations of blood types with the Rh factors:
Rh Positive Blood Types:
A+, B+, 0+ and AB+
Rh Negative Blood Types:
A-, B-, 0- and AB-
Rh factors are genetically determined. A baby may have the blood type and Rh factor of either parent, or a combination of both parents. Rh factors follow a common pattern of genetic inheritance. The Rh-positive gene is dominant (stronger) and even when paired with an Rh-negative gene, the positive gene takes over.
If a person has the genes + +, the Rh factor in the blood will be positive.
If a person has the genes + -, the Rh factor will also be positive.
If a person has the genes - -, the Rh factor will be negative.

⁣An adjective is a word that modifies or describes a noun or pronoun. Adjectives can be used to describe the qualities of someone or something independently or in comparison to something else. Examples: Adjectives in a sentence I like old houses.

⁣The environment is everything around us. All our surroundings including the air, soil, water, plants, and animals make up the environment. Plants and animals need a healthy environment to survive. An ecosystem is an area where living organisms interact in a specific way with the local environment to survive.

⁣Your favourite thing or person of a particular type is the one you like most.

⁣The “onset” is the initial phonological unit of any word (e.g. /c/ in cat) and the term “rime” refers to the string of letters that follow, usually a vowel and final consonants (e.g. /a/ /t/ in cat). Not all words have onsets

⁣A family tree is a chart that shows all the people in a family over many generations and their relationship to one another. Synonyms: lineage, genealogy, line of descent, ancestral tree More Synonyms of family tree.

⁣a garden in which plants (such as vegetables or herbs) for use in the kitchen are cultivated.

⁣There are six parts of a friendly letter:
First, we have the heading. The heading is the first thing you see on the letter. ...
Next is the greeting. ...
Third is the body of the letter. ...
Then we have the closing. ...
The fifth part of a friendly letter is the signature. ...
And finally, there is the postscript.

⁣A complex sentence is a sentence with one independent clause and at least one dependent clause. It works best when you need to provide more information to explain or modify your sentence's main point.

⁣Newspaper articles should:
Include facts. ...
Have a short, snappy and informative headline.
Provide a summary at the start explaining what happened (but not giving everything away!).
Use paragraphs to help the reader clearly understand the information.
Provide quotes to show people's opinions about the event.

⁣A simple sentence contains a subject and a verb, and it may also have an object and modifiers. However, it contains only one independent clause.

⁣A compound sentence joins two or more sentences that have related ideas of equal importance. The two sentences go together. Each sentence or independent clause must still have a subject and a verb. For example: She wanted spinach salad; he wanted a hamburger.