Biology Notes
Q.1. In which process of cellular resporation complete oxidation takes place?
Ans. In aerobic respiration complete oxidation of food material takes place.
Q.2. What is Cellular respiration?
Ans. The process of oxidation of food stuff to get energy is called cellular respiration.
Q.3. what is gaseous exchange?
Ans. Taking in Oxygen and given out carbon dioxide is termed as Gaseous Exchange.
Q.4. What is Breathing?
Ans. The term breathing is used for the process by which animals take air in their bodies to get oxygen from it and then give out the air to get rid of carbon dioxide.
Q.5. what is stomata?
Ans. The small opennings present in the epidermis of young stems and leaves by which gaseous exchange takes place are called stomata.
Q.6.
Q.1. In which process of cellular resporation complete oxidation takes place?
Ans. In aerobic respiration complete oxidation of food material takes place.
Q.2. What is Cellular respiration?
Ans. The process of oxidation of food stuff to get energy is called cellular respiration.
Q.3. what is gaseous exchange?
Ans. Taking in Oxygen and given out carbon dioxide is termed as Gaseous Exchange.
Q.4. What is Breathing?
Ans. The term breathing is used for the process by which animals take air in their bodies to get oxygen from it and then give out the air to get rid of carbon dioxide.
Q.5. what is stomata?
Ans. The small opennings present in the epidermis of young stems and leaves by which gaseous exchange takes place are called stomata.
Q.6.
Chapter Summary
All HTML elements can have attributes
The HTML title attribute provides additional "tool-tip" information
The HTML href attribute provides address information for links
The HTML width and height attributes provide size information for images
The HTML alt attribute provides text for screen readers
At W3Schools we always use lowercase HTML attribute names
At W3Schools we always quote attributes with double quotes
Below is an alphabetical list of some attributes often used in HTML:
Attribute Description
alt Specifies an alternative text for an image
disabled Specifies that an input element should be disabled
href Specifies the URL (web address) for a link
id Specifies a unique id for an element
src Specifies the URL (web address) for an image
style Specifies an inline CSS style for an element
title Specifies extra information about an element (displayed as a tool tip)
value Specifies the value (text content) for an input element.
Tag Description
<html> Defines an HTML document
<body> Defines the document's body
<head> Defines the document's head element
<h1> to <h6> Defines HTML headings
<hr> Defines a horizontal line
Tag Description
<p> Defines a paragraph
<br> Inserts a single line break
<pre> Defines pre-formatted text
style="property:value"
Chapter Summary
Use the style attribute for styling HTML elements
Use background-color for background color
Use color for text colors
Use font-family for text fonts
Use font-size for text sizes
Use text-align for text alignment
HTML Text Formatting Elements
Tag Description
<b> Defines bold text
<em> Defines emphasized text
<i> Defines italic text
<small> Defines smaller text
<strong> Defines important text
<sub> Defines subscripted text
<sup> Defines superscripted text
<ins> Defines inserted text
<del> Defines deleted text
<mark> Defines marked/highlighted text
Tag Description
<abbr> Defines an abbreviation or acronym
<address> Defines contact information for the author/owner of a document
<bdo> Defines the text direction
<blockquote> Defines a section that is quoted from another source
<dfn> Defines the definition of a term or an abbreviation.
<q> Defines a short inline quotation
<cite> Defines the title of a work
HTML <bdo> for Bi-Directional Override
The HTML <bdo> element defines bi-directional override.
The <bdo> element is used to override the current text direction:
Example
<bdo dir="rtl">This text will be written from right to left</bdo>
HTML Computer Code Elements
Tag Description
<code> Defines programming code
<kbd> Defines keyboard input
<samp> Defines computer output
<var> Defines a mathematical variable
<pre> Defines preformatted text
HTML Comments
« Previous
Next Chapter »
Comment tags <!-- and --> are used to insert comments in HTML.
HTML Comment Tags
You can add comments to your HTML source by using the following syntax:
<!-- Write your comments here -->
Styling HTML with CSS
CSS stands for Cascading Style Sheets
Styling can be added to HTML elements in 3 ways:
Inline - using a style attribute in HTML elements
Internal - using a <style> element in the HTML <head> section
External - using one or more external CSS files
The most common way to add styling, is to keep the styles in separate CSS files. But, in this tutorial, we use internal styling, because it is easier to demonstrate, and easier for you to try it yourself.
CSS Syntax
CSS styling has the following syntax:
element { property:value; property:value }
The element is an HTML element name. The property is a CSS property. The value is a CSS value.
Multiple styles are separated with semicolon.
Internal Styling (Internal CSS)
An internal style sheet can be used to define a common style for all HTML elements on a page.
Internal styling is defined in the <head> section of an HTML page, using a <style>element:
Example
<!DOCTYPE html>
<html>
<head>
<style>
body {background-color:lightgrey}
h1 {color:blue}
p {color:green}
</style>
</head>
<body>
<h1>This is a heading</h1>
<p>This is a paragraph.</p>
</body>
</html>
Chapter Summary
Use the HTML style attribute for inline styling
Use the HTML <style> element to define internal CSS
Use the HTML <link> element to refer to an external CSS file
Use the HTML <head> element to store <style> and <link> elements
Use the CSS color property for text colors
Use the CSS font-family property for text fonts
Use the CSS font-size property for text sizes
Use the CSS border property for visible element borders
Use the CSS padding property for space inside the border
Use the CSS margin property for space outside the border
The id Attribute
All the examples above use CSS to style HTML elements in a general way.
To define a special style for one special element, first add an id attribute to the element:
Example
<p id="p01">I am different</p>
then define a different style for the (identified) element:
Example
p#p01 {
color:blue;
}
Try it Yourself »
The class Attribute
To define a style for a special type (class) of elements, add a class attribute to the element:
Example
<p class="error">I am different</p>
Now you can define a different style for all elements with the specified class:
Example
p.error {
color:red;
}
HTML Style Tags
Tag Description
<style> Defines style information for a document
<link> Defines a link between a document and an external resource
HTML Links - Syntax
In HTML, links are defined with the <a> tag:
<a href="url">link text</a>
HTML Links - Colors
When you move the mouse over a link, two things will normally happen:
The mouse arrow will turn into a little hand
The color of the link element will change
By default, a link will appear like this (in all browsers):
An unvisited link is underlined and blue
A visited link is underlined and purple
An active link is underlined and red
You can change the default colors, by using styles:
Example
<style>
a:link {color:green; background-color:transparent; text-decoration:none}
a:visited {color:pink; background-color:transparent; text-decoration:none}
a:hover {color:red; background-color:transparent; text-decoration:underline}
a:active {color:yellow; background-color:transparent; text-decoration:underline}
</style>
Target Value Description
_blank Opens the linked document in a new window or tab
_self Opens the linked document in the same frame as it was clicked (this is default)
_parent Opens the linked document in the parent frame
_top Opens the linked document in the full body of the window
framename Opens the linked document in a named frame
Example
First, create a bookmark with the id attribute:
<h2 id="tips">Useful Tips Section</h2>
Then, add a link to the bookmark ("Useful Tips Section"), from within the same page:
<a href="#tips">Visit the Useful Tips Section</a>
Or, add a link to the bookmark ("Useful Tips Section"), from another page:
Example
<a href="html_tips.htm#tips">Visit the Useful Tips Section</a>
Chapter Summary
Use the HTML <a> element to define a link
Use the HTML href attribute to define the link address
Use the HTML target attribute to define where to open the linked document
Use the HTML <img> element (inside <a>) to use an image as a link
Use the HTML id attribute (id="value") to define bookmarks in a page
Use the HTML href attribute (href="#value") to address the bookmark
HTML Link Tags
Tag Description
<a> Defines a hyperlink
Chapter Summary
Use the HTML <img> element to define an image
Use the HTML src attribute to define the URL of the image
Use the HTML alt attribute to define an alternate text for an image, if it cannot be displayed
Use the HTML width and height attributes to define the size of the image
Use the CSS width and height properties to define the size of the image (alternatively)
Use the CSS float property to let the image float
Use the HTML <map> element to define an image-map
Use the HTML <area> element to define the clickable areas in the image-map
Use the HTML <img>'s element usemap attribute to point to an image-map
Tag Description
<img> Defines an image
<map> Defines an image-map
<area> Defines a clickable area inside an image-map
Lang attribute is used dor language
<a href> is used for a link
All HTML elements can have attributes
The HTML title attribute provides additional "tool-tip" information
The HTML href attribute provides address information for links
The HTML width and height attributes provide size information for images
The HTML alt attribute provides text for screen readers
At W3Schools we always use lowercase HTML attribute names
At W3Schools we always quote attributes with double quotes
Below is an alphabetical list of some attributes often used in HTML:
Attribute Description
alt Specifies an alternative text for an image
disabled Specifies that an input element should be disabled
href Specifies the URL (web address) for a link
id Specifies a unique id for an element
src Specifies the URL (web address) for an image
style Specifies an inline CSS style for an element
title Specifies extra information about an element (displayed as a tool tip)
value Specifies the value (text content) for an input element.
Tag Description
<html> Defines an HTML document
<body> Defines the document's body
<head> Defines the document's head element
<h1> to <h6> Defines HTML headings
<hr> Defines a horizontal line
Tag Description
<p> Defines a paragraph
<br> Inserts a single line break
<pre> Defines pre-formatted text
style="property:value"
Chapter Summary
Use the style attribute for styling HTML elements
Use background-color for background color
Use color for text colors
Use font-family for text fonts
Use font-size for text sizes
Use text-align for text alignment
HTML Text Formatting Elements
Tag Description
<b> Defines bold text
<em> Defines emphasized text
<i> Defines italic text
<small> Defines smaller text
<strong> Defines important text
<sub> Defines subscripted text
<sup> Defines superscripted text
<ins> Defines inserted text
<del> Defines deleted text
<mark> Defines marked/highlighted text
Tag Description
<abbr> Defines an abbreviation or acronym
<address> Defines contact information for the author/owner of a document
<bdo> Defines the text direction
<blockquote> Defines a section that is quoted from another source
<dfn> Defines the definition of a term or an abbreviation.
<q> Defines a short inline quotation
<cite> Defines the title of a work
HTML <bdo> for Bi-Directional Override
The HTML <bdo> element defines bi-directional override.
The <bdo> element is used to override the current text direction:
Example
<bdo dir="rtl">This text will be written from right to left</bdo>
HTML Computer Code Elements
Tag Description
<code> Defines programming code
<kbd> Defines keyboard input
<samp> Defines computer output
<var> Defines a mathematical variable
<pre> Defines preformatted text
HTML Comments
« Previous
Next Chapter »
Comment tags <!-- and --> are used to insert comments in HTML.
HTML Comment Tags
You can add comments to your HTML source by using the following syntax:
<!-- Write your comments here -->
Styling HTML with CSS
CSS stands for Cascading Style Sheets
Styling can be added to HTML elements in 3 ways:
Inline - using a style attribute in HTML elements
Internal - using a <style> element in the HTML <head> section
External - using one or more external CSS files
The most common way to add styling, is to keep the styles in separate CSS files. But, in this tutorial, we use internal styling, because it is easier to demonstrate, and easier for you to try it yourself.
CSS Syntax
CSS styling has the following syntax:
element { property:value; property:value }
The element is an HTML element name. The property is a CSS property. The value is a CSS value.
Multiple styles are separated with semicolon.
Internal Styling (Internal CSS)
An internal style sheet can be used to define a common style for all HTML elements on a page.
Internal styling is defined in the <head> section of an HTML page, using a <style>element:
Example
<!DOCTYPE html>
<html>
<head>
<style>
body {background-color:lightgrey}
h1 {color:blue}
p {color:green}
</style>
</head>
<body>
<h1>This is a heading</h1>
<p>This is a paragraph.</p>
</body>
</html>
Chapter Summary
Use the HTML style attribute for inline styling
Use the HTML <style> element to define internal CSS
Use the HTML <link> element to refer to an external CSS file
Use the HTML <head> element to store <style> and <link> elements
Use the CSS color property for text colors
Use the CSS font-family property for text fonts
Use the CSS font-size property for text sizes
Use the CSS border property for visible element borders
Use the CSS padding property for space inside the border
Use the CSS margin property for space outside the border
The id Attribute
All the examples above use CSS to style HTML elements in a general way.
To define a special style for one special element, first add an id attribute to the element:
Example
<p id="p01">I am different</p>
then define a different style for the (identified) element:
Example
p#p01 {
color:blue;
}
Try it Yourself »
The class Attribute
To define a style for a special type (class) of elements, add a class attribute to the element:
Example
<p class="error">I am different</p>
Now you can define a different style for all elements with the specified class:
Example
p.error {
color:red;
}
HTML Style Tags
Tag Description
<style> Defines style information for a document
<link> Defines a link between a document and an external resource
HTML Links - Syntax
In HTML, links are defined with the <a> tag:
<a href="url">link text</a>
HTML Links - Colors
When you move the mouse over a link, two things will normally happen:
The mouse arrow will turn into a little hand
The color of the link element will change
By default, a link will appear like this (in all browsers):
An unvisited link is underlined and blue
A visited link is underlined and purple
An active link is underlined and red
You can change the default colors, by using styles:
Example
<style>
a:link {color:green; background-color:transparent; text-decoration:none}
a:visited {color:pink; background-color:transparent; text-decoration:none}
a:hover {color:red; background-color:transparent; text-decoration:underline}
a:active {color:yellow; background-color:transparent; text-decoration:underline}
</style>
Target Value Description
_blank Opens the linked document in a new window or tab
_self Opens the linked document in the same frame as it was clicked (this is default)
_parent Opens the linked document in the parent frame
_top Opens the linked document in the full body of the window
framename Opens the linked document in a named frame
Example
First, create a bookmark with the id attribute:
<h2 id="tips">Useful Tips Section</h2>
Then, add a link to the bookmark ("Useful Tips Section"), from within the same page:
<a href="#tips">Visit the Useful Tips Section</a>
Or, add a link to the bookmark ("Useful Tips Section"), from another page:
Example
<a href="html_tips.htm#tips">Visit the Useful Tips Section</a>
Chapter Summary
Use the HTML <a> element to define a link
Use the HTML href attribute to define the link address
Use the HTML target attribute to define where to open the linked document
Use the HTML <img> element (inside <a>) to use an image as a link
Use the HTML id attribute (id="value") to define bookmarks in a page
Use the HTML href attribute (href="#value") to address the bookmark
HTML Link Tags
Tag Description
<a> Defines a hyperlink
Chapter Summary
Use the HTML <img> element to define an image
Use the HTML src attribute to define the URL of the image
Use the HTML alt attribute to define an alternate text for an image, if it cannot be displayed
Use the HTML width and height attributes to define the size of the image
Use the CSS width and height properties to define the size of the image (alternatively)
Use the CSS float property to let the image float
Use the HTML <map> element to define an image-map
Use the HTML <area> element to define the clickable areas in the image-map
Use the HTML <img>'s element usemap attribute to point to an image-map
Tag Description
<img> Defines an image
<map> Defines an image-map
<area> Defines a clickable area inside an image-map
Lang attribute is used dor language
<a href> is used for a link