Biology is the science of life — from the tiniest cell to the most complex human systems. This category is designed to support school students (Classes 6–12) as well as undergraduate (UG) learners with clear explanations, exam-focused content, and concept-building resources. You’ll find:
Concept-wise explanations aligned with NCERT and common UG syllabi
Important questions & answers for school exams, NEET foundation, and college tests
Human physiology, genetics, ecology, biotechnology, and cell biology explained simply
Practice questions, MCQs, and revision notes to strengthen understanding
Doubt-solving and conceptual clarity for competitive and academic success
Whether you’re preparing for school exams , building a strong base for NEET , or studying Biology at the undergraduate level , this section helps you learn smarter, revise faster, and understand Biology deeply — not just memorize it.
Learn life sciences the right way — clear concepts, exam relevance, and real understanding.
Q. During which stage of embryonic development does implantation occur?
A.
Zygote stage
B.
Blastocyst stage
C.
Gastrula stage
D.
Neurula stage
Show solution
Solution
Implantation occurs during the blastocyst stage when the embryo attaches to the uterine wall.
Correct Answer:
B
— Blastocyst stage
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Q. During which stage of human development does the heart begin to beat?
A.
Gastrulation
B.
Neurulation
C.
Embryonic stage
D.
Fetal stage
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Solution
The heart begins to beat during the embryonic stage, typically around the 6th week of gestation.
Correct Answer:
C
— Embryonic stage
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Q. During which trimester does the majority of organ development occur?
A.
First trimester
B.
Second trimester
C.
Third trimester
D.
All trimesters equally
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Solution
The first trimester is critical for organogenesis, where most major organs begin to form.
Correct Answer:
A
— First trimester
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Q. How do plants adapt their photosynthesis process in low light conditions?
A.
Increase chlorophyll production
B.
Decrease water usage
C.
Reduce carbon fixation
D.
Increase respiration rate
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Solution
Plants may increase chlorophyll production to enhance light absorption in low light conditions.
Correct Answer:
A
— Increase chlorophyll production
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Q. How do plants adapt to low light conditions in terms of photosynthesis?
A.
Increasing chlorophyll concentration
B.
Decreasing leaf area
C.
Reducing water uptake
D.
Increasing respiration rate
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Solution
Plants adapt to low light conditions by increasing chlorophyll concentration to capture more light.
Correct Answer:
A
— Increasing chlorophyll concentration
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Q. How do plants utilize the products of the light reactions?
A.
For cellular respiration only
B.
To synthesize proteins
C.
To fuel the dark reactions
D.
To produce more chlorophyll
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Solution
Plants use ATP and NADPH produced in the light reactions to fuel the dark reactions (Calvin cycle).
Correct Answer:
C
— To fuel the dark reactions
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Q. How does exercise affect the circulatory system?
A.
It decreases heart rate
B.
It increases blood flow and heart rate
C.
It reduces blood volume
D.
It has no effect
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Solution
Exercise increases blood flow and heart rate to meet the higher oxygen demands of the body during physical activity.
Correct Answer:
B
— It increases blood flow and heart rate
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Q. How does increased carbon dioxide concentration affect photosynthesis?
A.
Decreases rate
B.
Increases rate
C.
No effect
D.
Inhibits light reactions
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Solution
Increased carbon dioxide concentration generally increases the rate of photosynthesis up to a point.
Correct Answer:
B
— Increases rate
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Q. How does plant classification aid in ecological research?
A.
By simplifying plant interactions
B.
By providing a framework for understanding biodiversity
C.
By eliminating the need for field studies
D.
By focusing only on agricultural plants
Show solution
Solution
Plant classification provides a framework for understanding biodiversity and ecological interactions.
Correct Answer:
B
— By providing a framework for understanding biodiversity
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Q. How does smoking affect the respiratory system?
A.
Improves lung capacity
B.
Increases mucus production
C.
Enhances oxygen absorption
D.
Reduces risk of infections
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Solution
Smoking increases mucus production in the respiratory system, leading to blockages and respiratory issues.
Correct Answer:
B
— Increases mucus production
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Q. How does the availability of light affect the rate of photosynthesis?
A.
It has no effect
B.
Increases the rate until a saturation point
C.
Decreases the rate
D.
Only affects the dark reactions
Show solution
Solution
The rate of photosynthesis increases with light availability until it reaches a saturation point.
Correct Answer:
B
— Increases the rate until a saturation point
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Q. How does the concentration of carbon dioxide affect the rate of photosynthesis?
A.
Increases rate
B.
Decreases rate
C.
No effect
D.
Only affects light reactions
Show solution
Solution
Increasing the concentration of carbon dioxide generally increases the rate of photosynthesis up to a certain point.
Correct Answer:
A
— Increases rate
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Q. How does the concentration of CO2 affect the rate of photosynthesis?
A.
Increases it indefinitely
B.
Has no effect
C.
Increases it to a point, then levels off
D.
Decreases it
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Solution
The rate of photosynthesis increases with CO2 concentration to a point, after which it levels off due to other limiting factors.
Correct Answer:
C
— Increases it to a point, then levels off
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Q. How does the diaphragm contribute to breathing?
A.
By filtering air
B.
By contracting and relaxing to change lung volume
C.
By producing sound
D.
By transporting oxygen
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Solution
The diaphragm contracts and relaxes to change the volume of the thoracic cavity, facilitating inhalation and exhalation.
Correct Answer:
B
— By contracting and relaxing to change lung volume
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Q. How long does food typically stay in the stomach before moving to the small intestine?
A.
1-2 hours
B.
2-4 hours
C.
4-6 hours
D.
6-8 hours
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Solution
Food typically stays in the stomach for about 2 to 4 hours before moving to the small intestine.
Correct Answer:
B
— 2-4 hours
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Q. How long should items be exposed to ethylene oxide gas for effective sterilization?
A.
1 hour
B.
4 hours
C.
8 hours
D.
12 hours
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Solution
Items should be exposed to ethylene oxide gas for at least 8 hours for effective sterilization.
Correct Answer:
C
— 8 hours
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Q. How many bones are in the adult human skeleton?
A.
206
B.
210
C.
215
D.
220
Show solution
Solution
The adult human skeleton consists of 206 bones.
Correct Answer:
A
— 206
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Q. How many calories does the average human digestive system process in a day?
A.
1500
B.
2000
C.
2500
D.
3000
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Solution
The average human digestive system processes about 2000 calories per day.
Correct Answer:
B
— 2000
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Q. How many chambers does a typical mammalian heart have?
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Solution
A typical mammalian heart has 4 chambers: two atria and two ventricles.
Correct Answer:
C
— 4
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Q. How many chambers does the human heart have?
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Solution
The human heart has 4 chambers: two atria and two ventricles.
Correct Answer:
A
— 4
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Q. How many chromosomes are present in a human sperm cell?
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Solution
A human sperm cell contains 23 chromosomes.
Correct Answer:
A
— 23
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Q. How many chromosomes do most diploid plants have?
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Solution
Most diploid plants have 20 chromosomes, as they typically have two sets of 10.
Correct Answer:
B
— 20
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Q. How many classes are there in the division Angiospermae?
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Solution
There are 2 main classes in the division Angiospermae: Monocotyledons and Dicotyledons.
Correct Answer:
B
— 2
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Q. How many days does it typically take for a primary immune response to peak after initial exposure to an antigen?
A.
1-2 days
B.
3-7 days
C.
10-14 days
D.
21-28 days
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Solution
The primary immune response usually peaks around 10-14 days after the initial exposure to an antigen.
Correct Answer:
C
— 10-14 days
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Q. How many different classes of antibodies are there in humans?
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Solution
Humans have five different classes of antibodies: IgA, IgD, IgE, IgG, and IgM.
Correct Answer:
C
— 5
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Q. How many different types of enzymes are produced in the human digestive system?
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Solution
The human digestive system produces approximately 20 different types of enzymes.
Correct Answer:
B
— 20
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Q. How many hours of light do most plants require for optimal photosynthesis per day?
A.
6 hours
B.
12 hours
C.
18 hours
D.
24 hours
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Solution
Most plants require around 12 hours of light for optimal photosynthesis.
Correct Answer:
B
— 12 hours
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Q. How many layers of cells typically make up the epidermis in dicotyledonous plants?
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Solution
The epidermis in dicotyledonous plants typically consists of a single layer of cells.
Correct Answer:
A
— 1
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Q. How many liters of air does an average adult inhale in a minute at rest?
A.
4-6 L
B.
6-8 L
C.
8-10 L
D.
10-12 L
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Solution
An average adult inhales about 4-6 liters of air per minute at rest.
Correct Answer:
A
— 4-6 L
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Q. How many major divisions are there in the plant kingdom?
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Solution
There are 4 major divisions in the plant kingdom: Bryophyta, Pteridophyta, Gymnospermae, and Angiospermae.
Correct Answer:
B
— 4
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