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How do they help ni preventing fertilization

Posted by Rojinawaikhom Wao 6 years, 2 months ago

1 answers

Meghna Thapar 5 years, 9 months ago

The prevention of pregnancy in women (by preventing fertilisation) is called contraception. There are four methods of contraception:

Barrier method: In barrier method of contraception, the physical devices such as condoms are used by males and females.
Chemical method: In chemical methods of preventing pregnancy, the females use two types of pills – oral pills and vaginal pills.
Intra-Uterine Contraceptive Devices – The use of intra-uterine contraceptive devices like Copper-T is very effective in preventing pregnancy. A Copper-T is placed inside the uterus by a doctor to prevent unwanted pregnancies.
Surgical method: These methods are available for males as well as for females. Vasectomy is done in males and tubectomy is done in females.

Vasectomy - In males, a small portion of the sperm duct (Vasdeferens) is removed by surgical operation and both the cut ends are ligated properly. This prevents the sperms from coming out.
Tubectomy - In females, a small portion of the oviducts is removed by surgical operation and the cut ends are ligated. This prevents the ovum from entering into the oviducts.

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What are implants

Posted by Rojinawaikhom Wao 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Shiristi Gujjar 6 years, 2 months ago

These r a type of contraceptive..... These r implanted under our skin.... ND release hormones in our blood which prevents pregnancy

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Exine or sporopollenin which one is more resistant?

Posted by Quantum Gaming 6 years, 2 months ago

CBSE > Class 12 > Biology

4 answers

Anup Kumar 6 years, 2 months ago

It is the most hardest and indestructible substance found on the earth and can be stored as such for a longer time and also exine is the name given to the pollen grain's outermost layer and sporopollenin is material from which it is made

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Muskaan Vig 6 years, 2 months ago

Exine is made up of sporopollenin.that is why it is said that it is absent at some places where germ pore is present means sporpollenin is absent there.

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Ishika Gupta 6 years, 2 months ago

Sporopollenin is a chemical compound which is the most resistant organic substance found on the upper layer of exine

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Annu Khandey 6 years, 2 months ago

Bro exine is itself made up of sporopollenin so both are same

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Differentiate btw the genetic codes given below : (a) Unambiguous and universal (b) Degenerate and initiator

Posted by Shivangi Mishra 6 years, 2 months ago

CBSE > Class 12 > Biology

3 answers

Anup Kumar 6 years, 2 months ago

Degenerate here means when a specific amino acid is synthesised by more than one codon and initiator here specifying AUG codon which is starter and also codes for Methionine

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Anup Kumar 6 years, 2 months ago

Universal means genetic code is same form bacteria to humans

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Anup Kumar 6 years, 2 months ago

Unambiguous Means one codon codes for only one amino acid and it is always specific

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What is perigree analysis

Posted by Monalisha Yadav 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Annu Khandey 6 years, 2 months ago

Study of traits in a human family. For multiple of generation is called pedigree analysis

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What is an age-pyramid? (b) Name three representative kinds of age-pyramids for human population and list the characteristics for each one of them.

Posted by Ashna Khan 6 years, 2 months ago

CBSE > Class 12 > Biology

2 answers

Anup Kumar 6 years, 2 months ago

Hey we have this question in pegboard exam today ?

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Yogita Ingle 6 years, 2 months ago

A population at any given time is composed of individuals ages. If the age distribution (per cent individuals of a given age or age group) is plotted for these population, the resulting structure is called an age pyramid.

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What type of questions ask in section D?

Posted by Anmol S 6 years, 2 months ago

CBSE > Class 12 > Biology

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how to find out frequency of alleles

Posted by Aadarsh Singh 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Anup Kumar 6 years, 2 months ago

By using heinsburg's equation

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What are benthic animal

Posted by Kanak Lata Singh 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 6 years, 2 months ago

Benthic animals are organisms which live near seabed (benthic zone). They are also called as benthos. They feed on settling algae and bacteria. Example- sea stars, oysters etc.

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Pre reproductive in plant

Posted by Aaweza Fatima 6 years, 2 months ago

CBSE > Class 12 > Biology

0 answers

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Androgen synthesised by

Posted by Abhishek Sagar 6 years, 2 months ago

CBSE > Class 12 > Biology

2 answers

Priyanshu Patel 6 years, 2 months ago

leading cells in testis

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Amartya Sen 6 years, 2 months ago

Leydig cells

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What is pcr reaction

Posted by Toshan Gayakwad 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Annu Khandey 6 years, 2 months ago

Polymerase chain reaction for more consult chapter biotechnology in ncert

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Explain the role played by predators in a community

Posted by Hemant Mehta 6 years, 2 months ago

CBSE > Class 12 > Biology

2 answers

Muskaan Vig 6 years, 2 months ago

1.controlling prey population. 2.preserving diversity of different species by reducing competition between them. 3.transfer of energy to other trophic level

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Ashok Kumar 6 years, 2 months ago

Balancing of food chain

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What is embryogenesis

Posted by Suneel Bajpai Ji 82 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Jd Chouhan 6 years, 2 months ago

Defined as the development of embryo from zygote..

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Different between sexual and asexual reproduction

Posted by Fhnhvfigififi Hcogovivigi 6 years, 2 months ago

CBSE > Class 12 > Biology

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Androgens are synthesized by

Posted by Bidyaluxmi Thingnam 6 years, 2 months ago

CBSE > Class 12 > Biology

4 answers

Jd Chouhan 6 years, 2 months ago

Lyding cell

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Vanshita Sehrawat 6 years, 2 months ago

Leydig cells

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Dãñīyã Arshãd? 6 years, 2 months ago

Leydig cells

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Fhnhvfigififi Hcogovivigi 6 years, 2 months ago

Fjfnbcnf

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Lymphoid organ in human being

Posted by Nikhil Singh 6 years, 2 months ago

CBSE > Class 12 > Biology

2 answers

Ishika Gupta 6 years, 2 months ago

Bone marrow and spleen are major lymphoid organs

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Yogita Ingle 6 years, 2 months ago

The organs where origin and/or maturation and proliferation of lymphocytes occur are called lymphoid organs.

Lymphoid organs are of two types-

1. Primary lymphoid organs

2. Secondary lymphoid organs.

The primary lymphoid organs are bone marrow and thymus where immature lymphocytes differentiate into antigen-sensitive lymphocytes.

The bone marrow is the main lymphoid organ where all blood cells including lymphocytes are produced.

The secondary lymphoid organs provide the sites for interaction of lymphocytes with the antigen, which then proliferate to become effector cells.

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Why do we say that there is no natural death of single celled organisms

Posted by Devender Saharan 6 years, 2 months ago

CBSE > Class 12 > Biology

2 answers

Suneel Bajpai Ji 82 6 years, 2 months ago

Yes

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Yogita Ingle 6 years, 2 months ago

In single-celled organisms like Amoeba and bacteria the parental body itself divides into two parts and becomes daughter cells. Each of these divided cells rapidly grows into adult organisms. Therefore, the parent cannot be said to have died, it continues living as daughter cells.

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How many bones of appendicular skeleton is found in our body?

Posted by Ns H 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 6 years, 2 months ago

The appendicular skeleton consists of 126 bones in the adult and includes all of the bones of the upper and lower limbs plus the bones that anchor each limb to the axial skeleton.

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Give examples of those organisms which have double stranded RNA

Posted by Fiza Mehta 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Muskaan Vig 6 years, 2 months ago

Viruses have dsRNA- double stranded RNA. eg.yeast dsRNA virus L-A

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Different between convergent and divergent

Posted by Kamal Kamal Thory 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Gaurav Seth 6 years, 2 months ago

<th>BASIS FOR COMPARISION</th> <th>CONVERGENT EVOLUTION</th> <th>DIVERGENT EVOLUTION</th>

Meaning	When one or more different species evolve similarities in their characteristics and functions because of adaptations in an environment.	When an ancestral species diverges into multiple different species, ultimately giving rise to new species.
Way of evolution	They evolve from the different species but develops similar characteristics, like wings of birds and insects.	They evolve from same species and gradually give rise to new species like Darwin finches which have evolved in around 80 new species.
Cause of evolution	It is due to change in environmental conditions, or due to the place where they are living.	Due to migration or may be due to environmental changes.
Way of living	They live closely in the same way as other species, of which it has adapted the changes.	They live in different ways from their ancestor.
Appearance	The outer structure of a species may be different, but internally they resemble their ancestors.	As this type give rise to totally new species, they can be different from outside as well as inside in appearance.

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What is hind 2

Posted by Ishs Tyagi 6 years, 2 months ago

CBSE > Class 12 > Biology

5 answers

Aa Hh 6 years, 2 months ago

Simply we can say it is 1st restriction endonuclease

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Muskaan Vig 6 years, 2 months ago

It was the first restriction enzyme(endonuclease) isolated from bacteria . Later more restriction enzymes were isolated. It cut at specific sites in dna called recognition sites (for hind2). Hind 2 cut at specific sites after recognising length of six base pair(GTYRAC) called recognition sequence.

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Gayatri Challa 6 years, 2 months ago

Role: to cut DNA at particular palindromic sequences(recognised sequences)

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Gayatri Challa 6 years, 2 months ago

It is the first restriction endonuclease

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Ishs Tyagi 6 years, 2 months ago

And what is the role of molecular shesr

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why predation is important in biodiversity rich ecosystem

Posted by Tenzin Gechr 6 years, 2 months ago

CBSE > Class 12 > Biology

2 answers

Aa Hh 6 years, 2 months ago

For controlling population of preys

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Vinati Srivastava 6 years, 2 months ago

There are reasons : 1) for keeping the prey population under control. 2) nature's way of transferring energy to higher trophic level. 3) predators help in maintaing species diversity in a community.

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Carbon cycle

Posted by Dheeraj Goswami 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Meghna Thapar 6 years, 1 month ago

 The Carbon Cycle: Carbon is an important constituent of organic compounds found in all living beings in the form of carbohydrates, fats, proteins and nucleic acids. Carbon is trapped in the surrounding air and water in the form of carbon dioxide. The consumers devour the organic carbon compounds that producers manufacture. Through respiration, both consumers and producers return carbon to the non-living environment in the form of carbon dioxide. Some carbon accumulates in wood for many years and is eventually returned to the atmosphere by fires or through consumption and respiration by fungi, bacteria and other detrivores. Volcanic eruption also releases carbon dioxide to the atmosphere. Carbon is incorporated into life-forms through the basic process of photosynthesis which is performed in the presence of Sunlight by all life-forms that contain chlorophyll. This process converts carbon dioxide from the atmosphere or dissolved in water into glucose molecules. These glucose molecules are either converted into other substances or used to provide energy for the synthesis of other biologically important molecules. The utilisation of glucose to provide energy to living things involves the process of respiration in which oxygen may or may not be used to convert glucose back into carbon dioxide. This carbon dioxide then goes back into the atmosphere. Another process that adds to the carbon dioxide in the atmosphere is the process of combustion where fuels are burnt to provide energy for various needs like heating, cooking, transportation and industrial processes. Carbon is thus cycled repeatedly through different forms by the various physical and biological activities.

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The zygote is a single cell and a human adult has about 100 trillion cells.Approximately how many division should the zygote undergo to form the adult,considering the fact that one cell division leads to the formation of two cells?

Posted by Hansika Raj 6 years, 2 months ago

CBSE > Class 12 > Biology

1 answers

Meghna Thapar 5 years, 6 months ago

The zygote undergoes cell division, or mitosis, in order to develop into an organism of trillions of cells. It also undergoes speciation early on in the development of the organism. In order to create an organism with 100 trillion cells, 50 trillion cells need to divide (one time of mitosis), and 25 trillion need to divide to make 50 trillion (two times of mitosis), and so on. The cell would have to repeat this process 40 times (one cell going under mitosis 40 times is equivalent to 1 times 2 to the 40th power, which equals 1 trillion).

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Which chromosome has maximum number of gene

Posted by Devraj Gurjar 6 years, 2 months ago

CBSE > Class 12 > Biology

2 answers

Aa Hh 6 years, 2 months ago

Chromosome 1 (2968)

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Yogita Ingle 6 years, 2 months ago

From the insights of the sequencing of the human genome, it is estimated that chromosome 1 which is the largest human chromosome has the maximum number of genes (around 3168 genes), while chromosome Y has the least number of genes (around 344 genes).

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reference to above systematic diagram of spermatogenesis and oogenesis answer the following question about 300 million spermatozoamay be present in the human males how many spermatids form

Posted by Rajesh Bhadkare 6 years, 2 months ago

CBSE > Class 12 > Biology