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

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

Ask Question

What are contrseptines explain 4 different non surgical contraseptives

Posted by Sneha Bm 6 years, 5 months ago

2 answers

Nishant Sharma 6 years, 5 months ago

Barrier method-condom,cervical cap,vault cap Natural method-coitus interruptus,lactational amenorrhea Chemical method-creams and jellies iud-lippes loop,cut Oral contraceptives Injectable-depo provera Implants-norplant Hope it would help-:)

0Thank You

Md Khan 6 years, 5 months ago

Contraceptive are the devices which are used to prevent pregnancy. E.g. CuT,Cut7,Multiload375,LNG20.etc.

3Thank You

ANSWER

Why does the size of morulla remains almost same as of that ovum

Posted by Sevti Mahave 6 years, 5 months ago

CBSE > Class 12 > Biology

2 answers

Nishant Sharma 6 years, 5 months ago

The main aim of rapid division is to increase the karyoplasmic index(kI)

0Thank You

Yogita Ingle 6 years, 5 months ago

The first priority of the zygote is to divide and make lots of new cells, so its first few days are spent in rapid mitotic division. The cell number doubles with each round of cell division, so there is an exponential increase in cell number. This division takes place so quickly that the cells do not have time to grow, so the 32 celled stage is called morula and is the same size as the zygote. At this point, the zona pellucida (a protective membrane of glycoproteins that had surrounded the egg cell) is still intact, which also limits the size of the morula.

1Thank You

ANSWER

Can u plz briefly describe the process of recombinant dna technology

Posted by Gayathri S Krishna 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

Meghna Thapar 5 years, 8 months ago

Recombinant DNA technology is a technique which changes the phenotype of an organism (host) when a genetically altered vector is introduced and integrated into the genome of the organism. So, basically, the process involves introducing a foreign piece of DNA into the genome, which contains our gene of interest. This gene, which is introduced is the recombinant gene and the technique is called the recombinant DNA technology. Embedding the desired gene into the genome of the host is not as simple as it sounds. Developing a recombinant DNA involves a series of sequential steps which are discussed below.

Process of Recombinant DNA Technology

Recombinant DNA technology involves the selection of the desired gene for administration into the host followed by a selection of the perfect vector with which the gene has to be integrated and recombinant DNA formed. This recombinant DNA, then has to be introduced into the host. And at last, it has to be maintained in the host and carried forward to the offsprings.

0Thank You

ANSWER

What is anatropous ovule?

Posted by Abhishek Kumar Mishra 6 years, 5 months ago

CBSE > Class 12 > Biology

2 answers

Abhishek Kumar Mishra 6 years, 5 months ago

Right answer

0Thank You

Gaurav Seth 6 years, 5 months ago

Anatropous ovule :
a completely inverted ovule turned back 180 degrees on its stalk. ovule - a small body that contains the female germ cell of a plant; develops into a seed after fertilization.

function :
A flower is a plant's reproductive structure. One major part is the carpel, the female reproductive structure that includes the ovary . Inside the ovary is an ovule that, when fertilized, will develop into a seed. A seed contains an embryo (baby plant), the endosperm (food for the embryo), and a seed coat.

2Thank You

ANSWER

Difference between cmis and amis

Posted by Rahul Gond 6 years, 5 months ago

CBSE > Class 12 > Biology

2 answers

Rahul Gond 6 years, 5 months ago

Thanks you

0Thank You

Yogita Ingle 6 years, 5 months ago

Humoral Immunity Or Antibody Mediated Immune System (AMIS):

1. It consists of B-lymphocytes which produce the antibodies that circulate in the body fluids.

2. It defends the body against viruses and bacteria.

3. It does not respond to transplants.

4. It does not provide immunity against cancer.

Cell Mediated Immunity Or Cell Mediated Immune System (CMIS):

1. It consists of T-lymphocytes which produce normally 4 types of T-cells.

2. It defends the body against all pathogens including fungi and protozoa.

3. It reacts against transplants.

4. It provides immunity against cancer.

1Thank You

ANSWER

what is primary follicle and secondary follicle

Posted by Ayushi Singh 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

Disha Verma 6 years, 5 months ago

Primary oocyte gets surrounded by a layer of granulosa cell called primary follicle. The primary follicle get surrounded by more granulosa cells and new theca to form secondary follicle.

2Thank You

ANSWER

How does the study of different parts of a flower help in identifying wind as the pollinating agents

Posted by Dalip Singh Mehra 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

Shudhanshu Vikram Singh 6 years, 5 months ago

The plants having exposed anther and stigma are generally pollinated through wind.Example-China rose. So by study of anther and stigma we can identify wind as pollinating agent.

0Thank You

ANSWER

What is nectar

Posted by Shivam Yadav 6 years, 5 months ago

CBSE > Class 12 > Biology

3 answers

Shalini Roy 6 years, 5 months ago

flower juice

0Thank You

Aditya Dubey 6 years, 5 months ago

It is a reward for pollinators (which are responsible for pollination)

0Thank You

Raj Singh 6 years, 5 months ago

A sugary fluid secreted within flowers to encourage pollination by insects and other animals, collected by bees to make into honey.

3Thank You

ANSWER

Mention the advantages of selecting pea plant for experiment by Mendel

Posted by Deshu Deshu 6 years, 5 months ago

CBSE > Class 12 > Biology

2 answers

Raj Singh 6 years, 5 months ago

1. Short life span. 2. Many phenotypic character.

0Thank You

Yogita Ingle 6 years, 5 months ago

Mendel selected a pea plant because of the following features.

(a) Peas have many visible contrasting characters such as tall/dwarf plants, round/wrinkled seeds, green/yellow pod, purple/white flowers, etc.

(b) Peas have bisexual flowers and therefore undergo self pollination easily. Thus, pea plants produce offsprings with same traits generation after generation.

(c) In pea plants, cross pollination can be easily achieved by emasculation in which the stamen of the flower is removed without affecting the pistil.

(d) Pea plants have a short life span and produce many seeds in one generation.

1Thank You

ANSWER

What is the organism called that produces a foreign gene product?

Posted by Sourav Guleria 6 years, 5 months ago

CBSE > Class 12 > Biology

2 answers

Sourav Guleria 6 years, 5 months ago

Can we call it as Competent host or not

0Thank You

Gaurav Kumar 6 years, 5 months ago

Transgenic Organism.

1Thank You

ANSWER

What is mean by carrier? Plz anyone tell me

Posted by Sri Ragul 6 years, 5 months ago

CBSE > Class 12 > Biology

3 answers

Julis Bell 6 years, 5 months ago

Vector like insects, parasites which carries disease from one person to another

0Thank You

Harsh Sharma 6 years, 5 months ago

The person who is not affected because the characters are recessive in him and not able to express but these can pass from the perspn to his child in which it can become dominant/recessive trait If dominant then he has disease If recessive he become carrier for particular disease

0Thank You

Parul Singh 6 years, 5 months ago

Carrier is. Person who is responsible for the disease taking forward to the next generation.

0Thank You

ANSWER

Describe the developement of pollen grains

Posted by Sundram Bolt 6 years, 5 months ago

CBSE > Class 12 > Biology

2 answers

An Saraswat 6 years, 5 months ago

In flower ,the stemen contain a bilobed structure called anther. And anther divided into 2 sac called anther lobes or sacs by the connective tissue And each lobe is further divided into 2 theca by the septum And form microspore tetrad which have 4 microsporangium

1Thank You

M!Ń! ?? 6 years, 5 months ago

In flowering plants, pollen grains are formed within the anther. As the anther develops, four patches of tissue grow and become four chambers or pollen sacs. ... The microspores within the chambers are almost ready to become pollen grains but first they must undergo three more changes which occur almost simultaneously.

0Thank You

ANSWER

Egrets are often seen along with grazing cattles.What do you refer to this interaction?Give a reason for this association

Posted by Bhubaneshwor Oinam 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

Meghna Thapar 5 years, 8 months ago

The interaction in egrets and grazing cattle is called commensalism.

(i) In this association, egrets are found close to the grazing cattle.

(ii) During movement, the cattle flush out various insects which may be difficult for the egrets to catch.

(iii) The egrets are benefitted, but the cattle are neither benefitted nor harmed.

0Thank You

ANSWER

Selectable marker

Posted by Jeet Sa 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

M!Ń! ?? 6 years, 5 months ago

➡ It helps to select the host cells which contain the vector and eliminate the non transformants. ➡ Transformation is defined asthe procedure by which a piece of DNA is introduced into a bacterial cell. ➡ Genes encoding resistance to antibiotics like ampicillin, chloramphenicol, tetracycline or kanamycin, are useful selectable markers for E. Coli. ➡ The normal E. Coli cells do not carry resistance against any of these antibiotics.

1Thank You

ANSWER

In evolution chapter means of mya1.5

Posted by Bipen Singh 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

Raman Brar 6 years, 5 months ago

1.5 million year ago

1Thank You

ANSWER

Practical guide

Posted by Sneha Kumari 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

Nishant Sharma 6 years, 5 months ago

For practicals it's better to use youtube and rest depends on your knowledge

1Thank You

ANSWER

What is khheroff law

Posted by Himanshu Sahu 6 years, 5 months ago

CBSE > Class 12 > Biology

2 answers

Neha Jaiswal 6 years, 5 months ago

In biology it's a chargaff law

0Thank You

Parul Singh 6 years, 5 months ago

Kirchhoff's law is having 2 rule: 1. Junction rule: the algebric sum of the current meeting at a junction is always 0. 2. Loop rule: in a loop rule the algebric sum of the product of the I(current) & R(resistance) is equal to the algebric sum of the emf.

1Thank You

ANSWER

Explain mode of action of EcoRI

Posted by Laxmi Myra 6 years, 5 months ago

CBSE > Class 12 > Biology

2 answers

Harshit Singhal 6 years, 5 months ago

Not required

0Thank You

Parul Singh 6 years, 5 months ago

It is a restriction enzyme that cleaves DNA double helix in fragments or pieces at specific sites. It is also a part of restriction modification and in molecular biology used as restriction enzyme. It creates 4 sticky nucleitide ends.

0Thank You

ANSWER

What is the basic principle of variation

Posted by Laxmi Myra 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

M!Ń! ?? 6 years, 5 months ago

The fundamental principle of valuation is that the value of any financial asset is the present value of the expected cash flows. This principle applies regardless of the financial asset.

0Thank You

ANSWER

Latest sample paper of bio 2019 -20based pattern cbse

Posted by Rajat Sharma 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

Disha Verma 6 years, 5 months ago

Arihant

1Thank You

ANSWER

Who proposed chromosomal theory of linkage

Posted by Laxmi Myra 6 years, 5 months ago

CBSE > Class 12 > Biology

3 answers

Anshuman Kumar 6 years, 5 months ago

Th morgon

0Thank You

Shivam Yadav 6 years, 5 months ago

T.H morgan Thomas hunt Morgan

0Thank You

Anjali Kaushik 6 years, 5 months ago

Walter sutton nd theode boveri .

0Thank You

ANSWER

Factors that affect harshley weinberg equilibrium

Posted by Laxmi Myra 6 years, 5 months ago

CBSE > Class 12 > Biology

2 answers

Shivam Yadav 6 years, 5 months ago

Genetic drift Natural selection

0Thank You

Priya Upadhyay 6 years, 5 months ago

There are five factors that affect it 1 Gene pool 2 Mutation 3 Genetic drift 4 Genetic recombination 5 Natural selection

1Thank You

ANSWER

Function of dna ligase

Posted by Laxmi Myra 6 years, 5 months ago

CBSE > Class 12 > Biology

3 answers

M!Ń! ?? 6 years, 5 months ago

It has important role in the process of DNA replication and DNA repair. It has three general functions: It seals repairs in the DNA, it seals recombination fragments, and it connects Okazaki fragments (small DNA fragments formed during the replication of double-stranded DNA).

0Thank You

Raman Brar 6 years, 5 months ago

It helps to join the okazaki fragments in strand of dna.

0Thank You

Anjali Kaushik 6 years, 5 months ago

DNA ligase enzyme act as glue which helps to join the foregin dna with vector dna nd as a result r dna is formed.

0Thank You

ANSWER

Function of dna polymerase

Posted by Laxmi Myra 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

Anjali Kaushik 6 years, 5 months ago

Dna polymerase helps in replication process.

1Thank You

ANSWER

Describe tetrasomic monosomic nullisomic

Posted by Laxmi Myra 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

Nishant Sharma 6 years, 5 months ago

Basically it is type of aneupliody-no. Of chromosome is different than basic set of chromosomes Tetrasomic- (2n+2) it has two extra chromosomes Monosomic- (2n-1) it has 1 defecient chromosome Nullisomic- (2n-2) it is defecient in having 2 chromosomes Hope it will help :)

0Thank You

ANSWER

What is biotech

Posted by Ayush Sharma 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

M!Ń! ?? 6 years, 5 months ago

Biotechnology deals with microorganisms, plant or animal cells or their enzyme to produce products and processes useful to humans.

0Thank You

ANSWER

the importance of genetic drift in evolution fitness of population helps in evolution. Give reason

Posted by Laxmi Myra 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

Raman Brar 6 years, 5 months ago

Genetic drift means that gene get isolated from particular gene pool due to some reasons and isolated population develop variation to adapt themself to changing enviornment and this led to evolution.

0Thank You

ANSWER

Which one is better mode of reproduction 1. Sexual 2. Asexual and why?

Posted by Ayan Ansari 6 years, 5 months ago

CBSE > Class 12 > Biology

0 answers

ANSWER

What are bioremediation

Posted by Nikita Parakh 6 years, 5 months ago

CBSE > Class 12 > Biology

1 answers

Anshuman Kumar 6 years, 5 months ago

Bioremediation is a branch of bioteachnology which use living organism like bacteria ,microbes to to remove contaminants , pollutants and toxins from soil.

0Thank You

ANSWER

Describe the mechanism of pattern of inheritance of ABO blood group in human

Posted by Shankar Lamjel 6 years, 5 months ago

CBSE > Class 12 > Biology

2 answers

Raman Brar 6 years, 5 months ago

Multiple alleleism and co dominance

1Thank You

Yogita Ingle 6 years, 5 months ago

In humans, the ABO blood groups are controlled by a gene called I gene. It has three alleles, namely IA, IB and i. A person possesses any two of the three alleles. IA and IB dominate over i. But with each other, IA and IB are co-dominant that is they both get expressed when present together.
IA and IB are responsible for the production of antigen A and B present on the surface of RBC. Plasma membrane of RBC possess sugar polymer that protrudes out of its surface and the type of sugar present on the surface is controlled by gene I. IA and IB allele is responsible for coding for glycosyltransferase enzyme responsible for developing modification in the terminal sugar molecule. IA and IB differ very minutely on the sugar molecule while gene i does not produce any sugar molecule. Here allele A and B are dominant in nature while ii fail to produce any antigenic molecule so express blood group O.