Find the best tutors and institutes for Class 12 Tuition
Q17:
Examine a few flowers of any cucurbit plant and try to identify the staminate and pistillate flowers. Do you know any other plant that bears unisexual flowers?
Solution :
Step 1: Morphological Basis of Unisexuality in Cucurbits
Members of the family Cucurbitaceae (which includes pumpkins, cucumbers, and gourds) exhibit a reproductive morphology known as dicliny, meaning they produce unisexual flowers. Each flower possesses only one type of reproductive organ. A single cucurbit plant typically bears both staminate (male) and pistillate (female) flowers on the same individual plant [This botanical condition is termed as being monoecious, mathematically represented as $1 \text{ plant} : 2 \text{ flower sexes}$].
Step 2: Key Diagnostic Features for Identification
To accurately identify and differentiate the staminate and pistillate flowers of a cucurbit plant, one must examine the base of the flower (the pedicel-receptacle junction) and the floral whorls present.
| Diagnostic Feature | Staminate Flower (Male) | Pistillate Flower (Female) |
|---|---|---|
| Reproductive Organs | Contains only the androecium (stamens). Lacks a functional gynoecium. | Contains only the gynoecium (carpels/pistil). Lacks functional stamens. |
| Base of the Flower | The base of the corolla (petals) attaches directly to a slender stem (pedicel). No swelling is observed. | Features an inferior ovary. There is a distinct, swollen structure at the base of the petals that resembles a miniature fruit (e.g., a tiny cucumber or pumpkin). |
| Core Center Whorl | Yellow, pollen-bearing anthers are visible in the center. | A lobed stigma (for receiving pollen) is prominent in the center. |
Step 3: Visual Representation of Floral Morphology
The structural difference, particularly the position of the ovary [Per the epigynous floral arrangement in females], is the most definitive identification marker.
Step 4: Identification of Other Plants Bearing Unisexual Flowers
Unisexual flowers are an evolutionary adaptation to promote cross-pollination (xenogamy) and increase genetic diversity. Plants that bear unisexual flowers are categorized into two botanical groups:
- Monoecious Plants [Both male and female flowers on the same plant]:
- Maize (Corn): The tassels at the top are staminate inflorescences, while the ears (cobs) on the stem are pistillate inflorescences.
- Castor (Ricinus communis): Bears unisexual flowers on the same raceme.
- Coconut (Cocos nucifera): Bears both types of flowers on the same inflorescence.
- Dioecious Plants [Male and female flowers on separate individual plants]:
- Papaya (Carica papaya): A plant is strictly male (producing only pollen) or strictly female (producing fruit).
- Date Palm (Phoenix dactylifera): Requires separate male trees to pollinate female, fruit-bearing trees.
- Mulberry (Morus alba): Generally dioecious, bearing separate male and female catkins.
Final Solution: Staminate and pistillate flowers of cucurbits can be easily identified by examining the floral base; pistillate (female) flowers possess a distinct, swollen inferior ovary resembling a miniature fruit at the base of the petals, whereas staminate (male) flowers lack this swelling and only contain pollen-bearing anthers. Other common plants bearing unisexual flowers include Maize, Castor, and Coconut (Monoecious), as well as Papaya, Date Palm, and Mulberry (Dioecious).
More Questions from Class 12 Biology Reproduction in Organisms EXERCISES
- Q1: Why is reproduction essential for organisms?
- Q1: Why is reproduction essential for organisms?
- Q2: Which is a better mode of reproduction: sexual or asexual? Why?
- Q2: Which is a better mode of reproduction: sexual or asexual? Why?
- Q3: Why is the offspring formed by asexual reproduction referred to as clone?
- Q3: Why is the offspring formed by asexual reproduction referred to as clone?
- Q4: Offspring formed due to sexual reproduction have better chances of survival. Why? Is this statement always true?
- Q4: Offspring formed due to sexual reproduction have better chances of survival. Why? Is this statement always true?
- Q5: How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction?
- Q5: How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction?
- Q6: Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction?
- Q6: Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction?
- Q7: What is vegetative propagation? Give two suitable examples.
- Q7: What is vegetative propagation? Give two suitable examples.
- Q8(a): Define (a) Juvenile phase,
- Q8(a): Define (a) Juvenile phase,
- Q8(b): Define (b) Reproductive phase,
- Q8(b): Define (b) Reproductive phase,
- Q8(c): Define (c) Senescent phase.
- Q8(c): Define (c) Senescent phase.
- Q9: Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?
- Q9: Higher organisms have resorted to sexual reproduction in spite of its complexity. Why?
- Q10: Explain why meiosis and gametogenesis are always interlinked?
- Q10: Explain why meiosis and gametogenesis are always interlinked?
- Q11(a): Identify each part in a flowering plant and write whether it is haploid (\(n\)) or diploid (\(2n\)). (a) Ovary ———————————
- Q11(a): Identify each part in a flowering plant and write whether it is haploid ((n)) or diploid ((2n)). (a) Ovary ———————————
- Q11(b): Identify each part in a flowering plant and write whether it is haploid (\(n\)) or diploid (\(2n\)). (b) Anther ———————————
- Q11(b): Identify each part in a flowering plant and write whether it is haploid ((n)) or diploid ((2n)). (b) Anther ———————————
- Q11(c): Identify each part in a flowering plant and write whether it is haploid (\(n\)) or diploid (\(2n\)). (c) Egg ———————————
- Q11(c): Identify each part in a flowering plant and write whether it is haploid ((n)) or diploid ((2n)). (c) Egg ———————————
- Q11(d): Identify each part in a flowering plant and write whether it is haploid (\(n\)) or diploid (\(2n\)). (d) Pollen ———————————
- Q11(d): Identify each part in a flowering plant and write whether it is haploid ((n)) or diploid ((2n)). (d) Pollen ———————————
- Q11(e): Identify each part in a flowering plant and write whether it is haploid (\(n\)) or diploid (\(2n\)). (e) Male gamete ———————————
- Q11(e): Identify each part in a flowering plant and write whether it is haploid ((n)) or diploid ((2n)). (e) Male gamete ———————————
- Q11(f): Identify each part in a flowering plant and write whether it is haploid (\(n\)) or diploid (\(2n\)). (f) Zygote ———————————
- Q11(f): Identify each part in a flowering plant and write whether it is haploid ((n)) or diploid ((2n)). (f ) Zygote ———————————
- Q12: Define external fertilisation. Mention its disadvantages.
- Q12: Define external fertilisation. Mention its disadvantages.
- Q13: Differentiate between a zoospore and a zygote.
- Q13: Differentiate between a zoospore and a zygote.
- Q14: Differentiate between gametogenesis from embryogenesis.
- Q14: Differentiate between gametogenesis from embryogenesis.
- Q15: Describe the post-fertilisation changes in a flower.
- Q15: Describe the post-fertilisation changes in a flower.
- Q16: What is a bisexual flower? Collect five bisexual flowers from your neighbourhood and with the help of your teacher find out their common and scientific names.
- Q16: What is a bisexual flower? Collect five bisexual flowers from your neighbourhood and with the help of your teacher find out their common and scientific names.
- Q17: Examine a few flowers of any cucurbit plant and try to identify the staminate and pistillate flowers. Do you know any other plant that bears unisexual flowers?
- Q18: Why are offspring of oviparous animals at a greater risk as compared to offspring of viviparous animals?
- Q18: Why are offspring of oviparous animals at a greater risk as compared to offspring of viviparous animals?
CBSE Solutions for Class 12 Biology Reproduction in Organisms
Chapters in CBSE - Class 12 Biology
- Human Reproduction
- Reproductive Health
- Principles of Inheritance and Variation
- Molecular Basis of Inheritance
- Evolution
- Human Health and Disease
- Strategies for Enhancement in Food Production
- Microbes in Human Welfare
- Biotechnology: Principles and Processes
- Biotechnology and Its Applications
- Organisms and Populations
- Ecosystem
- Biodiversity and Conservation
- Environmental Issues
Top Tutors who teach Reproduction in Organisms
Top Tutor
Tezpur Airpur Area, Tezpur
7 yrs of
Exp
2 students
421 hrs of classes completed
450
per hour
Online Classes
Tutor's home
I am a mathematics teacher. I have been working in schools from last 6-7 years , and i was giving tutions at my home and even in an insitute in delhi from last 5-7 years. I shifted to tezpur,Assam in April 2021. my last job was in air force school hindan and I currently work at Air force school tezpur. i have a degree in msc mathematics and b.ed. i teach mathematics upto class 12. my key skills are in ms office , mathematics project, calligraphy , and can help out students in their various activities.
She is really amazing tutor you can ever have.She guides her students really well.She helps her students everytime. She motivates her students always. She supports her students always. She explains really nicely.
Top Tutor
P847+PC6 Thrissur, Thrissur
17 yrs of
Exp
10 students
501 hrs of classes completed
600
per hour
Online Classes
I believe in conceptual learning and always relate the content to real life situations. I discourage the rote learning and promote the application of the concept in daily life situation.
I have enjoyed madam's classes a lot. Her sessions are very engaging. She has helped me to understand even the difficult concepts easily.
Super Tutor
Panvel, Mumbai
12 yrs of
Exp
21 students
3283 hrs of classes completed
500
per hour
Online Classes
I provide private tuition for Physics and Mathematics for Class XI and XII (All Boards) Physics for Engineering Aspirants Physics for Medical Aspirants Class IX and X Mathematics and Science.
I am grateful that my son have been taught by you. Your dedication, knowledge, and passion for teaching make every class engaging and productive. You explain complex concepts in a simple and understandable manner. Thank you Sir .
Super Tutor
Lalpur, Ranchi
9 yrs of
Exp
8 students
3155 hrs of classes completed
600
per hour
Online Classes
I am a qualified and dedicated teacher, having 10 years of teaching and research experience across different boards including CBSE, ICSE, IGCSE, IB, GCSE, and Australian Board. I specialize in guiding students from Class 8 to Post Graduation, helping them achieve academic excellence with a tailored and engaging teaching approach. I bring in-depth knowledge and expertise to my sessions. Qualifications: • Ph. D (Science) – BIT Mesra, Ranchi • CSIR UGC NET (2011) AIR-14 • ICAR NET (2010) • ICAR NET (2018) • GATE (2009) My student-centered approach focuses on assessing individual learning needs, bridging knowledge gaps, and fostering critical thinking through interactive methods like discussions, visual aids, and hands-on activities. Regular feedback and personalized guidance empower students to excel and develop a lifelong love for learning.
Well explained and great teacher with patience, ensures we understand the concepts clearly. Well organised as well. Thank you for helping
Top Tutor
Krishnarajapura, Bangalore
10 yrs of
Exp
5 students
399 hrs of classes completed
500
per hour
Online Classes
Tutor's home
I am an IITian. Passed out from IIT Delhi. Teaching is my passion. I have seven years of teaching experience teach chemistry, Biology ,Biochemistry, Biotechnology for class 11 and 12 from different boards.I teach chemistry for entrance exams like NEET, JEE.
Anasuya mam teaches each topic in detail and giving excellent support in JEE chemistry preparations.
