Distinguish between unisexual and bisexual flowers giving one example of each. Draw a diagram showing process of germination of pollen grains on stigma and label the following parts :
(i) Female germ cell
(ii) Male germ cell
(iii) Ovary
OR
Draw a diagram of human female reproductive system and label the part
(i) that produces eggs.
(ii) where fusion of egg and sperm takes place.
(iii) where zygote is implanted.
What happens to human egg when it is not fertilised ?
Distinguish between unisexual and bisexual flowers giving one example of each. Draw a diagram showing process of germination of pollen grains on stigma and label the following parts :
(i) Female germ cell
(ii) Male germ cell
(iii) Ovary
OR
Draw a diagram of human female reproductive system and label the part
(i) that produces eggs.
(ii) where fusion of egg and sperm takes place.
(iii) where zygote is implanted.
What happens to human egg when it is not fertilised ?
Part 1: Distinguishing Unisexual and Bisexual Flowers
| Feature | Unisexual Flower | Bisexual Flower |
|---|---|---|
| Definition | Contains either stamens (male reproductive part) or pistil (female reproductive part), but not both. | Contains both stamens (male reproductive part) and pistil (female reproductive part) in the same flower. |
| Examples | Papaya, Watermelon | Hibiscus, Mustard |
Part 2: Diagram of Germination of Pollen Grains on Stigma
- (i) Female germ cell: Located inside the ovule within the ovary.
- (ii) Male germ cell: Travels down through the pollen tube.
- (iii) Ovary: The swollen bottom part of the pistil.
OR Option
#### 1. Human Female Reproductive System Labels:
- (i) Part that produces eggs: Ovary.
- (ii) Part where fusion of egg and sperm takes place: Fallopian tube (Oviduct).
- (iii) Part where zygote is implanted: Uterus.
#### 2. What happens to a human egg when it is not fertilised?
- If the egg cell is not fertilised, it survives for about one day.
- Since the ovary releases one egg every month, the uterus prepares itself monthly to receive a fertilised egg by making its inner lining thick and spongy.
- When fertilisation does not occur, this lining is no longer required. Hence, the lining slowly breaks down and is discharged through the vagina along with blood and mucous. This monthly cycle is known as menstruation.
Marking Scheme
- 12 marks
- 21.5 marks
- 31.5 marks
- 43 marks
- 52 marks
Hint
Recall that papaya and watermelon are unisexual, while Hibiscus and mustard are bisexual. For the diagram, ensure the pollen tube is shown carrying the male gamete down the style to the egg cell inside the ovary.
Quick Oral Answer
Unisexual flowers contain either male (stamens) or female (pistil) reproductive parts, whereas bisexual flowers contain both. An example of a unisexual flower is papaya, and a bisexual flower is Hibiscus.
Analysis & Explanation
This question tests the student's understanding of plant and human reproduction.
- For the plant section, the distinction between unisexual and bisexual flowers is based directly on the presence of reproductive organs (stamens/pistils) as defined in the NCERT text. The diagram of pollen germination must clearly show the path of the pollen tube from the stigma, through the style, to the ovary containing the female germ cell.
- For the human female reproductive system, the functional roles of the ovary (egg production), fallopian tube (fertilisation site), and uterus (implantation site) are tested, along with the physiological process of menstruation when fertilisation fails to occur.
Common Mistakes
- 1Confusing the examples of unisexual and bisexual flowers.
- 2Drawing the pollen tube stopping midway in the style instead of reaching the ovary.
- 3Forgetting to mention that the unfertilised egg lives for only about one day before the uterine lining breaks down.
Interesting Facts
Some plants have lost the ability to produce seeds entirely (like banana and jasmine) and rely solely on vegetative propagation to reproduce!
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2012?
This question carries 5 marks in the CBSE Class 10 Science 2012 examination.
Which chapter does this question come from in Science?
This question is from the chapter "How do Organisms Reproduce?" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Sexual Reproduction in Flowering Plants" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2012 paper?
This is a Long Answer question from Section A in the CBSE Class 10 Science 2012 paper.