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Germination of pollen grain on stigma is – in-situ and in-vivo. how ?

Germination of pollen grain on stigma is – in-situ and in-vivo. how ?

/ NCERT LINE BY LINE, pre-class, Sexual Reproduction in flowering Plants / By Prof. Siddharth Sanghvi

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Pollen Germination Terms

Pollen Germination: Terms Explained

Question
Germination of pollen grain on stigma is:

(1) ex-situ
(2) in-situ
(3) in-vivo
(4) More than one correct
Answer
✅ Correct Answer: (2) in-situ and (3) in-vivo
➡️ So, option (4) “More than one correct” is the right choice.
Explanation
Germination on stigma happens inside the flower (living plant) ➡️ In Vivo.
And stigma is its natural site ➡️ In Situ.
So both are correct ✅✅.
Your Doubt, as asked in Class ?
Why ex-situ is not correct? Pollen grain moves from where it is produced (anther) to somewhere else (stigma). Isn’t this ex-situ?
Explanation ✅
Excellent observation by you but we often get confused here.

🔸 Pollen grain is produced in the anther.
🔸 It germinates on the stigma.

Now your thought: Pollen moves → so is this ex-situ?

❌ Answer: No. Because in biology, in situ refers to processes happening in their natural site of function, not the site of origin.
➡️ So, germination on stigma is still in situ.

Terms Definitions

In Vivo
Process occurs inside a living organism.
In Situ
Process occurs at its natural or original site.
Ex Situ
Process occurs outside its natural site in an artificial environment.
In Vitro
Process occurs outside organism in glass/lab conditions.

Future Ready Information

Process / Location In Vivo In Situ Ex Situ In Vitro
Pollen formation inside anther ✅ Yes ✅ Yes ❌ No ❌ No
Pollen germination on stigma (natural) ✅ Yes ✅ Yes ❌ No ❌ No
Pollen germination in lab (on medium) ❌ No ❌ No ✅ Yes ✅ Yes
Pollination (transfer anther to stigma) 🚫 Movement 🚫 Movement 🚫 Movement 🚫 Movement

Practice Questions

Q1
Where does in-vitro pollen germination occur?

✅ Answer: Outside organism in lab.
🔎 Explanation: In vitro means “in glass”, so it’s done in petri dishes or lab medium.
Q2
Is pollination an example of in situ process?

❌ Answer: No.
🔎 Explanation: Pollination is just movement, not a process of function at natural site.
Q3
Pollen germination on stigma in flower is called?

✅ Answer: In vivo and In situ.
🔎 Explanation: Happens inside plant (in vivo) and at its natural site (in situ).
Q4
Ex situ pollen germination is seen where?

✅ Answer: In laboratory.
🔎 Explanation: Ex situ is outside natural site, so lab medium is ex situ.
Q5
Formation of pollen in anther is?

✅ Answer: In vivo and In situ.
🔎 Explanation: Happens inside living plant and in its original site.

MCQ Practice Questions

Q1
Where does in-vitro pollen germination occur?

(1) Inside the organism
(2) Outside the organism in a lab
(3) In the natural environment
(4) On the stigma of the flower

✅ Answer: (2) Outside the organism in a lab
🔎 Explanation: In vitro means “in glass”, meaning it happens outside the organism, typically in lab conditions.
Q2
Pollination is an example of which process?

(1) In Vivo
(2) In Situ
(3) Ex Situ
(4) In Vitro

✅ Answer: (2) In Situ
🔎 Explanation: Pollination is the transfer of pollen from one flower to another, occurring at the plant’s natural site.
Q3
Pollen germination on stigma is best described as?

(1) In Vivo
(2) In Situ
(3) Ex Situ
(4) Both In Vivo and In Situ

✅ Answer: (4) Both In Vivo and In Situ
🔎 Explanation: Germination on stigma happens inside the plant (in vivo) and at the plant’s natural site (in situ).
Q4
Ex situ pollen germination can be observed in?

(1) Laboratory
(2) Natural environment
(3) On stigma
(4) Inside anther

✅ Answer: (1) Laboratory
🔎 Explanation: Ex situ means outside the natural site; lab conditions are where this would happen.
Q5
Which term describes the formation of pollen in anther?

(1) In Vivo
(2) In Situ
(3) Ex Situ
(4) In Vitro

✅ Answer: (1) In Vivo
🔎 Explanation: Pollen formation happens inside the living plant, so it is an example of “In Vivo”.

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