In view of the coronavirus pandemic, we are making LIVE CLASSES and VIDEO CLASSES completely FREE to prevent interruption in studies
Biology > Photosynthesis In Higher Plants > Introduction to Photosynthesis
Photosynthesis In Higher Plants

Introduction to Photosynthesis

We all know that plants can make their own food. Isn’t it an amazing thing? But did you know there are a few plants that cannot make their own nutrition? Let us have a detailed look at the incredible photosynthesis process and the factors that affect it.

Suggested Videos

Play
Play
Play
Arrow
Arrow
ArrowArrow
General Introduction to Photosynthesis
Factors affecting Photosynthesis
Introduction to Light Reactions and Dark Reactions
Slider

 

Photosynthesis

Plants who can make their own food are known as autotrophs. But, there are few plants who cannot and are called as heterotrophs. The process by which plants make their own food is called as photosynthesis. The photosynthesis process occurs largely in the leaves of the plant which are known as the ‘kitchen of the plant’. In some cases, even the stems have the potential to perform photosynthesis.

Browse more Topics under Photosynthesis In Higher Plants

The Leaf

Photosynthesis Process

(Source: Sqizzes.com)

As mentioned earlier, the process of photosynthesis occurs in the leaf of a plant. The leaf is anatomically divided into many layers. Photosynthesis occurs in the mesophyll layer of the leaf, the middle layer, also known as palisade parenchyma. These mesophyll cells are abundant in special cell organelles called as chloroplasts which are responsible for photosynthesis.

Leaves also contain small openings on their undersurface known as ‘stomata’ which are responsible for gaseous exchange and are the source of CO2 that enters the leaf.

The Chloroplast

Photosynthesis Process

(Source: AssignmentPoint.com)

These are special organelles that inside which photosynthesis process takes place. Chloroplasts are double membraned organelles. The Chloroplast consists of disc-shaped thylakoids that are stacked together. Stacked thylakoids are called a ‘grana’. It is in the membrane of the thylakoid that pigment chlorophyll is present.

Photosynthesis Process

Photosynthesis Process

(http://photosynthesiseducation.com)

Photosynthesis process can be divided into two stages:

 

Light Reaction

This reaction is a light- dependent reaction and it is needed to produce energy molecules like ATP and NADPH. This reaction occurs in the thylakoid membrane of the chloroplast where the sunlight triggers of the reaction of chlorophyll pigment.

The excited chlorophyll releases an electron which is accepted by the H2 of water after its splitting. The reactions that happen are redox reactions and ultimately lead to the production of energy molecules- ATP and NADPH which are then needed for the subsequent synthesizing reactions that occur in the dark reaction.

Dark Reaction

This reaction does not literally occur in the dark but is named so because it is independent of light. This reaction can occur both in the presence and absence of light. Due to the scientists who worked to discover this cycle, this reaction is also called as the Calvin- Benson-Bassham cycle.

This reaction occurs in the stroma of the chloroplast. This reaction uses the energy molecules generated in the light phase of photosynthesis and converts CO2 into glucose. The photosynthesis process can be summarised by the following equation:

6CO2+ 6H2O→C6H12O6+ 6O2 (in the presence of sunlight)

Factors Affecting Photosynthesis Process

There are few factors that promote or inhibit photosynthesis depending on their concentration :

  • Light
  • Temperature
  • CO2
  • Oxygen

Purpose of Photosynthesis

For the plants, photosynthesis helps generate glucose to be able to generate energy to perform other functions such as respiration, transport of water and minerals throughout the plant. Plants need energy to also perform other biological and biochemical processes to enable it to multiply. For other organisms, plants serve as food.

Solved Example for You

Q: Where does the light reaction occur? 

  1. Stroma of the Chloroplast
  2. Thylakoid membrane
  3. Grana
  4. Both b and c

Sol. (d) Chlorophyll is present in the thylakoid membrane of the chloroplasts. Stacked thylakoids are known as grana. So, both options b and c are correct.

Share with friends

Customize your course in 30 seconds

Which class are you in?
5th
6th
7th
8th
9th
10th
11th
12th
Get ready for all-new Live Classes!
Now learn Live with India's best teachers. Join courses with the best schedule and enjoy fun and interactive classes.
tutor
tutor
Ashhar Firdausi
IIT Roorkee
Biology
tutor
tutor
Dr. Nazma Shaik
VTU
Chemistry
tutor
tutor
Gaurav Tiwari
APJAKTU
Physics
Get Started

1
Leave a Reply

avatar
1 Comment threads
0 Thread replies
1 Followers
 
Most reacted comment
Hottest comment thread
1 Comment authors
Ranjeeta Recent comment authors
  Subscribe  
newest oldest most voted
Notify of
Ranjeeta
Guest
Ranjeeta

How to remember the dark reaction in biology

Stuck with a

Question Mark?

Have a doubt at 3 am? Our experts are available 24x7. Connect with a tutor instantly and get your concepts cleared in less than 3 steps.

Download the App

Watch lectures, practise questions and take tests on the go.

Get Question Papers of Last 10 Years

Which class are you in?
No thanks.