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 phase of photosynthesis is carbon dioxide utilized?
A.
Light reactions
B.
Calvin cycle
C.
Photorespiration
D.
Electron transport chain
Show solution
Solution
Carbon dioxide is utilized during the Calvin cycle.
Correct Answer:
B
— Calvin cycle
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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
Show solution
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
Show solution
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
Show solution
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
Show solution
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 habitat fragmentation affect plant reproduction?
A.
Increases genetic diversity
B.
Reduces pollinator access
C.
Enhances seed dispersal
D.
Promotes hybridization
Show solution
Solution
Habitat fragmentation can isolate plant populations, limiting pollinator access and reducing reproductive success.
Correct Answer:
B
— Reduces pollinator access
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Q. How does increased atmospheric CO2 affect photosynthesis?
A.
Decreases photosynthesis
B.
Has no effect
C.
Increases photosynthesis up to a point
D.
Increases respiration
Show solution
Solution
Increased atmospheric CO2 can enhance photosynthesis rates up to a certain saturation point.
Correct Answer:
C
— Increases photosynthesis up to a point
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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
Show solution
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
Show solution
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
Show solution
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
Show solution
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
Show solution
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
Show solution
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
Show solution
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 are present in the gametes of a plant with a total of 30 chromosomes in its somatic cells?
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Solution
Gametes are haploid, so they will have half the number of chromosomes, which is 15.
Correct Answer:
A
— 15
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Q. How many chromosomes are typically found in the gametes of a diploid plant with 14 chromosomes?
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Solution
Gametes are haploid, so they contain half the number of chromosomes, which is 14/2 = 7.
Correct Answer:
A
— 7
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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 classes are there in the division Angiosperms?
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Solution
There are 2 classes in the division Angiosperms: Monocots and Eudicots.
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
Show solution
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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