ncert solutions for class 12th biology chapter 1- CBSE-exams

ncert solutions for class 12th biology chapter 1- CBSE-exams

Hi guys in this article you know about ncert solutions for class 12th biology chapter 1 reproduction in organism and their ncert solutions for class12 biology chapter 1- CBSE-JAC exams

■ subtopics:- reproduction in organism and ncert solutions for class 12th biology chapter 1- CBSE-JAC exams

* introduction :- ncert solutions for class 12 biology chapter 1- CBSE-JAC exams and students might be busy in your preparation for coming 12th board Jharkhand academic Council exams.biologysir.com will provide many type of education material like fill in the blanks, true or false matching type questions ,multiple choice questions, very short questions answers type, short questions answer type and long questions type of 12th class Biology from each topic that help you in your preparation.reproduction in organism

*In this post :- ncert solutions for class12 biology chapter 1- CBSE-JAC exams and we provide you matching type questions with answer from the lesson 1 reproduction in organism

ncert solutions for class 12th biology chapter 1

(Q1) why is reproduction essential for organisms?

Ans. Reproduction is essential for continuity of life of any species in a given time . its is only methods by which the thread of life is maintained. it enables the species to live generation after generation.

(Q2) which is better mode of reproduction sexual or Asexual why ?

Ans. Sexual reproduction is better mode of reproduction due to following reasons

A) sexual reproduction introduce variation in offspring that leads to evolutionary significance
B) sexual reproduction produce in child can adjust according to environment

C) better variety of offspring are produce due to combination of both male and female character

(Q3) how does the progeny formed from asexual reproduction different from those born by sexual reproduction

Ans. In asexual reproduction clones are produced by single parents without involvement of formation and fusion of gametes that’s why clone resembles the parents genetically and physiological and morphologically but sexual reproduction child are produced by biparents male and female with the involvement of formation and fusion of gametes and child are genetically and morphologically different of parents

(Q4) distinguish between Asexual and sexual reproduction ?why is vegetative reproduction also considered as type of asexual reproduction?

Ans.1 A) asexual reproduction is uniparental reproduction and sexual reproduction is bi parental reproduction

B) gametes formation and fusion not involved in asexual reproduction but in sexual reproduction gametes are formed and fuse to form zyogote

C) in asexual reproduction clones are produced which is genetically similar to parents but in sexual reproduction child are produce which is genetically different from the parents

2) vegetative reproduction is considered as type of a sexual reproduction because characters of parents resembles the new plant which are produced by vegetative reproduction. New individuals are arises from the different parts of plants like stem roots and leaves

(Q5) why is the offspring formed by Asexual Reproduction referred to as clone?

Ans. In asexual reproduction clones are produced that’s are identical and exact copies of their parents,and clones are genetically physiological and morphological similar to their parents

(Q6) offspring formed due to sexual reproduction have better chance of survival why?

Ans. 1) variation are produced by sexual reproduction in offspring that leads to evolutionary significance

2) child have better chance to adjust according to change in environment

3) better variety of offspring are produce by the combination of new character of both male and female parents

(Q7) what is vegetative propagation ?give two suitable example

Ans. It is a type of asexual reproduction in which new individuals are appear from any vegetative parts of plants from stem roots and leaves.
Examples :- 1) vegetative propagation by leaves in bryophyllum
2) vegetative propagation by stem in Ginger turmeric

(Q8) define a) Juvenile phase b) reproductive phase c) senescent phase

Ans. a) juvenile phase:- all organisms have to reach certain stage of growth and maturity in their life before they can reproduce .this period of growth is known as juvenile phase or vegetative phase

b) reproductive phase:- when organism gain maturity and start to reproduce formation of sperm and ova in animals and formation of flower in plant is reproductive phase of organism

c) senescent phase:- after the end of reproductive phase all the parameters of our body undergoes slow metabolism and ultimately leads to death

(Q9) higher organism had resorted to sexual reproduction inspite of its complexity why?

Ans. Sexual reproduction is present in most of the organisms and those organism which depend upon asexual reproduction for their multiplication like fungi and algae Swift on the sexual mode of reproduction due to adverse condition .it is due to appear from a asexual spors under unfavourable conditions change into gametes and leads to formation of zygote . time of origin of sex benefit accidentally by fusion of gametes that is called hunger theory of sex

(Q10) explain why meiosis and gametogenesis are always interlinked

Ans. Gametogenesis is the process of formation of two types of gametes male and female gamete that is a sperm and ova and we know that gametes are haploid cells. But majority of body are in diploid stage . so there is meiosis cell division by which diploid cells change into haploid cells so meiosis and gametogenesis are always interlinked to each other

(Q11) identify each part and write whether it is haploid or diploid

A) ovary- diploid
B) anther – diploid
C) egg – haploid
D) pollen -haploid
E) male gamete -haploid
F) zygoye – diploid

(Q12) define external fertilization and mention its dishadvantage

Ans. The fertilization in which fusions of gametes occurs in external medium like water outside the body of female organism. it is found in majority of fishes algae as well as frog.

Organised fish undergoes external fertilization should release large number of gametes and occasionally some gametes fuse to form zygote and large number of offspring are produced but such of springs are highly vulnerable to Predator and threating their survival up to adulthood.

(Q13) differentiate between zoospore and zygote

Ans. 1) zoospore formed during asexual reproduction in lower plants like fungi and Algae but zygote are formed due to fusion of male and female gametes in sexual reproduction

2) zoospore are haploid in nature but zygote is diploid in nature

3) zoospore are motile due to presence of flagella but zygote is non motile due to absent of locomotory organ

(Q14) differentiate between gametogenesis and embryogenesis

Ans. 1) gametogenesis is formation of gametes and embryogenesis is formation of embryo

2) in gametogenesis process gametes which are formed are haploid in nature but in embryogenesis process the embryo is diploid in nature

3) meiosis cell division is found in gametogenesis process but in the case of embryogenesis only mitosis cell division is found

(Q15) describe the post fertilization changes in flower

Ans. In flowering plants zygote is formed inside the ovules. after fertilization process sepal petals and stamens of the flower fall off and destroy. Zygote forms the embryo and ovule having embryo formed the seeds, ovary is develop into fruits and ovary wall develop into pericarp of fruit and ovule is develop into seed

(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 name

Ans. A flower which bears both male and female sex organ is called bisexual flower

1) mustard – brassica campestris
2) potato – solanum tuberosum
3) onion – allium cepa
4) rose – Rosa Indica
5) apple – pyrus malus

(Q17) examine a few flowers of any cucurbit plant and try to identify the staminate and pistillate flower . do you know any other plant that bears unisexual flower?

Ans. Study a flowering plants of family cucurbitaceae (Gourd family) like ghia tori it is observed that male flowers are present at the Summit of peduncles and female flowers are solitary . both male and female flowers are born on same plant

Male flowers bear 5 stamen in which carpel is absent and female flowers bears 3 fuse carpels inferior to ovary that is unilocular and parietal placentation .in that cash androecium is absent

(Q18) why offspring of oviparous animals are at greater risk

Ans. In oviparous animals the eggs are laid outside of body and whole of embryonic period and development is exposed to harmful environmental and biological factor and life is threating to predators so chance of death are in such cases