CBSE > Class 12 > Biology | CBSE Board | Homework Help

Ask questions which are clear, concise and easy to understand.

Ask Question

What is role of cervix in female reproductive system ?

Posted by Jasmeen Kaur 6 years, 9 months ago

4 answers

Somya Sharma 6 years, 9 months ago

cervix is the part of female reproductive system which connects the uterus to the ******.It's function is to allow flow of menstrual blood from the uterus into the ******, and direct the sperm into uterus during intercoarse....

3Thank You

Gursharn Kaur 6 years, 9 months ago

Allows the entry of semen during copulation Allow menstrual flow Helps doring parturition

1Thank You

Yamima Rai 6 years, 9 months ago

Cervix connect the uterus to the ******.The function of cervix is to allow the flow of menstrual blood from uterus.

1Thank You

Dharma Yadav 6 years, 9 months ago

To stop the pregnency

1Thank You

ANSWER

Which is the best youtube channel for class 12th ecology which is only based upon NCERT

Posted by Garima Dhingra 6 years, 9 months ago

CBSE > Class 12 > Biology

2 answers

Rishabh Soni 6 years, 9 months ago

Canvas classes

0Thank You

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

Biomentors is there but if you want only ncert based videos you go to videos provided by examfear.com

0Thank You

ANSWER

Which organelle is found only in plant cells

Posted by H V 6 years, 9 months ago

CBSE > Class 12 > Biology

4 answers

Sia ? 6 years, 9 months ago

chloroplasts
The two organelles found only in plant cells are chloroplasts and central vacuoles.

0Thank You

Rishabh Soni 6 years, 9 months ago

Vacuole

0Thank You

Ashish Singh 6 years, 9 months ago

Chloroplast and vacuole also but it was very small in animal cell

0Thank You

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

Vacuoles are also found in animal cell but are small in size.

0Thank You

ANSWER

Explain the process of oogenesis

Posted by Shreya Yadav 6 years, 9 months ago

CBSE > Class 12 > Biology

0 answers

ANSWER

Types of regeneration process

Posted by Subham Sahu 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 6 years, 9 months ago

Regeneration is one of the processes in which if an organism is cut into several pieces, each of its parts regrows to the original state. This process is carried out by specialized cells called stem cells. It takes place in organisms that have a very simple structure with very few specialized cells.
There are two types of regeneration:
Morphallaxis: This type of regeneration has little growth and depends upon tissues repatterning. For eg., Hydra grows by loss of cells from its end and by budding. When cut into two, the upper part develops into foot while the lower part develops into the head. The formation of nearby heads is inhibited by the head region.
Epimorphosis: This type of regeneration depends upon the growth of new and properly patterned structures. For eg., regeneration of a vertebrate limb. It involves cell dedifferentiation and growth. The epidermal cells form a blastema. The blastema gives rise to structures with positional distal values. Retinoic acid changes proximal-distal values in limb regeneration.

1Thank You

ANSWER

What is reverse of central dogma? Name the DNA formed in this process.

Posted by Vineet Garg 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

Central dogma states that how genetic information flows from DNA--- RNA---protein.Reverse central dogma explains how genetic information in some viruses flow from RNA to DNA in this way RNA----DNA----RNA----Protein .When informaion flows from RNA to DNA it is called reverse transcription.

1Thank You

ANSWER

Difference between secondary follicle and tertiary follicle?

Posted by Sanu Pandey 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

Secondary follicle is formed when primary follicle is surrounded by more layers of granulosa cells and form a new outer covering( theca).Similiarly, tertiary follicle is formed when secondary follicle develops a fluid filled cavity called antrum.It is the advanced form of secondary follicle. The difference is that tertiary follicle is bigger and has antrum which is absent in secondary follicle.Actually secondary follicle gets tranformed into tertiary follicle.

0Thank You

ANSWER

Explain the menstrual phase in human female.State the levels of ovarian and pituiary hormones during this phase.

Posted by Raja Sahu 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

In a28 days menstrual cycle, the menses take place on 3-5 daysof cycle.The production of LH from anterior lobe of pituitary gland is reduced.The withdrawal of this hormone causes degeneration of corpus luteum( secretes progesterone) and therefore progesterone production is reduced.Production of estrogen is also reduced in this phase.The endometrium of uterus breaks down and menstruation begins.The cells of endometrium secretions, blood and unfertilized ovum constitutes the menstrual flow.

0Thank You

ANSWER

How does a bisexual flowering plants ensure cross pollination

Posted by Ashif Ali 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

A bisexual flower has both androecium and gynoecium because of this self pollination occurs in most of the times but sometimes due to insect pollinators and wind, cross pollination may occur.Artificial techniques for cross pollination in such flowers can be used to ensure cross .p .One such method is emasculation(removal of anthers from flower )

1Thank You

ANSWER

All reproductive tract infections (RTIs) are STDs, but all STDs are not RTIs. justify with example.

Posted by Ďãřşháñăã Yadav ? ? ? 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

Sia ? 6 years, 9 months ago

Among the common STDs-gonorrhoea, syphilis, genital herpes, chlamydiosis, hepatitis-B, AIDs, etc., hepatitis-B, and AIDs are not infections of the reproductive organs though their mode of transmission could be through sexual contact also, AU other diseases are transmitted through sexual contact and are also infections of the reproductive tract.

0Thank You

ANSWER

what happens to the polar body after 2nd meiotic division?

Posted by Ďãřşháñăã Yadav ? ? ? 6 years, 9 months ago

CBSE > Class 12 > Biology

5 answers

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

Most welcome??

1Thank You

Ďãřşháñăã Yadav ? ? ? 6 years, 9 months ago

thanks mamta

0Thank You

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

A polar body is a small haploid cell that is formed as a result of unequal cytoplasmic division after meiosis and do not have the ability to fertilize.Polar bodies serve no purpose other than as a place to discard chromosomes ( which are of no use and remain after meiosis) .At present it is not certain whether the first polar body degenerate or divide further,but the second polar body is released in perivitelline space.

1Thank You

Ďãřşháñăã Yadav ? ? ? 6 years, 9 months ago

totally copied from Google. pls yarr try to answer in ur knowledge.

0Thank You

Sia ? 6 years, 9 months ago

Meiosis II, which actually forms the second polar body, occurs as a result of fertilisation. The secondary oocyte becomes a mature oocyte (ovum) by the expulsion of second polar body into perivitelline space. This results in completion of 2nd meiotic division.

0Thank You

ANSWER

Define oestrus and menstrual cycle

Posted by Vikash Muwal 6 years, 9 months ago

CBSE > Class 12 > Biology

2 answers

Kartik Singh Adhikari 6 years, 9 months ago

Menstrual Cycle ●Occurs in primates ●Bleeding phase occurs ¤Eg:Humans.....Monkeys.... Oestrus Cycle ●Occurs in non primates ●Bleeding phase does not occur ¤Eg:Cow...Dog....Cat....

1Thank You

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

Cyclical changes during reproductive phase in non primates mammals( eg- cow ,dog) is called oestrous cycle. The cyclical changes in primates( human, monkey) during reproductive phase is termed as menstrual cycle.

0Thank You

ANSWER

What do you mean by 1st trimester and 2nd trimester

Posted by Honey Singh 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

The first trimester is the time in between fertilization of egg by sperm (conception) and week 12 of pregnancy.The second trimester is time of pregnancy from week 13 to week 28

1Thank You

ANSWER

Make a chart describing male or female reproductive part

Posted by Shivangi Gupta 6 years, 9 months ago

CBSE > Class 12 > Biology

0 answers

ANSWER

Some organisms reproduse throughout the year. What are they called

Posted by Shagun Sharma 6 years, 9 months ago

CBSE > Class 12 > Biology

3 answers

Ďãřşháñăã Yadav ? ? ? 6 years, 9 months ago

arrey koi ni always welcome yarr... ✌️?

2Thank You

Shagun Sharma 6 years, 9 months ago

Thnx mujhe lag raha tha....but i was not sure?

3Thank You

Ďãřşháñăã Yadav ? ? ? 6 years, 9 months ago

they are known as continuous breeders.

2Thank You

ANSWER

What is infertility??

Posted by Sneha Chaudhary 6 years, 9 months ago

CBSE > Class 12 > Biology

2 answers

Ďãřşháñăã Yadav ? ? ? 6 years, 9 months ago

Infertility means failure of an organism to conceive and have children.

4Thank You

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

As per NCERT -Inability to concieve or produce children even after two years of unprotected sexual cohabitation is called infertility

2Thank You

ANSWER

What are Outbreeding Devices?

Posted by Gyan Singh 6 years, 9 months ago

CBSE > Class 12 > Biology

2 answers

Honey Singh 6 years, 9 months ago

Out breeding devices help in cross pollination. Following are the outbreeding devices 1.unisexuality.2dichogamy.3protandrous.4protogynous.5heterostyle.6herkogamy.7self incompability

1Thank You

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

Outbreeding devices are mechanisms which are followed by the plants in order to prevent self pollination.

2Thank You

ANSWER

Define and design a test -crot

Posted by Pankaj Kumar 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

Sia ? 6 years, 9 months ago

Test cross: A cross in which an individual with an unknown dominant phenotype is crossed with a recessive individual for that trait. So it is helpful in knowing the genotype (whether it is homozygous or heterozygous for the dominant trait) of an unknown individual.
Condition I: If the unknown is homozygous tall (TT) then crossing with dwarf recessive (tt) gives all tall offsprings (Tt).

Condition II: If the unknown is heterozygous tall (Tt), then crossing with dwarf results in 50% tall (Tt) and 50% dwarf (tt) progeny.

1Thank You

ANSWER

Define ruminate endosperm.

Posted by Jasmine Jasmine 6 years, 9 months ago

CBSE > Class 12 > Biology

2 answers

Jasmine Jasmine 6 years, 9 months ago

Thanks

0Thank You

Sia ? 6 years, 9 months ago

Ruminate endosperm, the condition in which the endosperm is dissected by in-growths of the seed coat, is a common condition in the palms. Ruminate endosperm forms when the seed coat intrudes inward via meristematic growth. In palms, growth of the seed coat may intrude the young endosperm.

0Thank You

ANSWER

What is test and back cross

Posted by Gagandeep Kaur 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 6 years, 9 months ago

Back cross is the cross that involves the mating of the F1 hybrid with one of its parent.
It can be explained with this example. Suppose a homozygous tall plant having genotype TT is crossed with the homozygous small plant having genotype tt, then their hybrid will be Tt (F1 plant). Now back cross is crossing this Tt individual with either TT or tt individual.
Test cross is a cross in which an individual with an unknown dominant phenotype is crossed with an individual (parent) homozygous recessive for that trait.

1Thank You

ANSWER

Appropriate definition of placenta

Posted by Samina Khan 6 years, 9 months ago

CBSE > Class 12 > Biology

2 answers

꧁≪Mämƭå ℭℏ۝ᑌĎℎàℜÿ? 6 years, 9 months ago

The placenta is a temporary organ that connrcts the developing foetus via umbilical cord to the uterine wall to allow nutrient uptake, thermoregulator, waste elimination and gas exchange via mother's blood supply; to fight against infectiom and to produce hormones which support pregnancy

1Thank You

Yogita Ingle 6 years, 9 months ago

Placenta: Placenta is a special umbilical cord that develops in the fourth week of pregnancy. It establishes an intimate connection between the foetal membrane and the uterine wall.

0Thank You

ANSWER

When and where does semination takes place

Posted by Swagato Karmakar 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

Sia ? 6 years, 9 months ago

If semen gets in the ******, the sperm cells can swim up through the cervix and uterus and into the fallopian tubes, looking for an egg. They have up to 6 days to find an egg before they die. When a sperm cell joins with an egg, it's called fertilization. Fertilization doesn't happen right away.

0Thank You

ANSWER

How many flowers in trees

Posted by Ram Sharma 6 years, 9 months ago

CBSE > Class 12 > Biology

2 answers

Pubg Pedi 6 years, 9 months ago

Pgll ho kya Tree ka size, type, shape , location , species , batawo, ja ke count karunga ,BC??

2Thank You

Mugha ? 6 years, 9 months ago

Many flowers in flowering trees

0Thank You

ANSWER

discuss about the development of female spore in the flowering plant?

Posted by Ankshuman Gohain 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

Mekya Tajo 6 years, 9 months ago

Development of female spore in the flowering plants by procces of megasporogenesis

0Thank You

ANSWER

Make a chart describe female and male reproductive system with digram

Posted by Deepanshu Rajput 6 years, 9 months ago

CBSE > Class 12 > Biology

0 answers

ANSWER

What is surrogacy

Posted by Shamsh Tabrez Khan 6 years, 9 months ago

CBSE > Class 12 > Biology

2 answers

Souromi Chatterjee 6 years, 9 months ago

The process is only performed after certain agreements between the couple and surrogate mother and even the couple need to invest certain amount of money on the surrogate mother

1Thank You

Souromi Chatterjee 6 years, 9 months ago

Surrogacy is a method of assisted reproductive techniques in which a egg and sperm is made to fertilise inside test tube by ivf and the zygote is implanted in the womb of another bearer who is called as the surrogate mother.. surrogacy is usually performed if the actual mother is incapable of carrying a baby in the uterus due to any medical disorders.. the implanted zygote draws nourishment and grows naturally inside the womb of the surrogate mother and after 9 months of gestation baby i s delivered and hand overed to the actual couple..

1Thank You

ANSWER

What is chromosome and its function

Posted by Manjeet Yadav 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 6 years, 9 months ago

Chromosomes are thread-like structures woven together . They are located inside the nucleus of animal and plant cells. Each chromosome happens to be made of proteins and a single molecule of deoxyribonucleic acid or commonly abbreviated to DNA.
Chromosomes basically control all the activities of a living cell. DNA present on the chromosome not only carries most of the genetic information but also controls the hereditary transference.
Chromosomes are essential for the process of cell division, are responsible for replication, division, and creation of daughter cells which contain correct sequences of DNA and proteins.
Chromosomes are often called as the 'packaging material', because it tightly holds the DNA and proteins together in the eukaryotic cells.

0Thank You

ANSWER

write the basis on which Alfred sturtevent explain gene maping_! I'm asking this question second time..

Posted by Ďãřşháñăã Yadav ? ? ? 6 years, 9 months ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 6 years, 9 months ago

Alfred Sturtevant was a student of Morgan who mapped the positions of genes on a chromosome by using the frequency of recombination between the gene pairs present on the same chromosome. He used the data obtained as a measure of distance between two genes. This process of mapping the gene positions was termed as 'gene mapping'.

2Thank You

ANSWER

Fetures of wind pillination

Posted by Ude Gill 6 years, 9 months ago

CBSE > Class 12 > Biology