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Ts root tips 10 points

Posted by Parveen Raj Kashyap 7 years, 1 month ago

CBSE > Class 12 > Biology

0 answers

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Experiment of pollen generation of flowers

Posted by Tanu Kumari 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Meghna Thapar 5 years, 8 months ago

When a pollen grain lands on the stigma of a flower of the correct species , a pollen tube begins to grow. It grows through the style until it reaches an ovule inside the ovary. The nucleus of the pollen then passes along the pollen tube and fuses (joins) with the nucleus of the ovule. The male organ of flowering plants consists of pollen and the sperm cells within. Pollen develops into a pollen tube, which is a single cell with a tubular structure. The tip of the pollen tube (anther) extends and grows into the pistil. Once a pollen grain settles on a compatible pistil, it may germinate in response to a sugary fluid secreted by the mature stigma. Lipids at the surface of the stigma may also stimulate pollen tube growth for compatible pollen.

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Name the algae whose cell division is itself mode of reproduction?

Posted by Silent Punk 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 7 years, 1 month ago

In Monerans and Protists, cell division is itself a mode of reproduction. Example: Bacteria and Amoeba respectively.

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Name the condition in vertebrate where the body attacks self cell.

Posted by Sonu Yadav 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Vibhav Tiwari 7 years, 1 month ago

Sometimes due to genetic and other unknown reasons the body attacks self cells. THIS RESULTS IN DAMAGE TO THE BODY AND IS CALLED AUTO IMMUNE DISEASE. Rheumatoid arthritis is one such case. Also some other cases where this happens is in:- Myasthenia gravis : antibodies are formed against acetylcholine receptors Pernicious anemia : antibodies against castle intrinsic factor. Hashimoto disease : antibodies against the thyroid gland. Rheumatoid arthritis Insulin dependent diabetes mellitus Type 1 : antibodies against Beta cells of pancreas. Multiple sclerosis : antibodies against myelin sheath of nerve cells.

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Aminosentesis

Posted by Devisharan Pachori 7 years, 1 month ago

CBSE > Class 12 > Biology

3 answers

Priyanshu Gupta 7 years, 1 month ago

a process in which amniotic fluid is sampled using a hollow needle inserted into the uterus, to screen for any abnormalities in the developing fetus.

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Tilak Raj Sharma 7 years, 1 month ago

*** = GENDER

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Tilak Raj Sharma 7 years, 1 month ago

there is a AMNIOTIC FLUID surrounds the develpoing embryo. and it contain a CHROMOSOMAL PATTERN on the basis of which one can check the *** OF FOETUS.. this medical process is known as AMNIOCENTESIS

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Chromosome no in cat

Posted by Aditya Goyal 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Ambuj Mishra?? 7 years, 1 month ago

Domestic cats have 38 chromosomes, as compared to 46 in humans. ... Some species of cat such as the ocelot have only 36 chromosomes, and breeding such a cat with a cat that has 38 chromosomes will result in offspring that have 37 chromosomes

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Sir/mam I want learn some resoning based of CBSE practical of 12th class I did't found content about it Please help me

Posted by Monster Hall 7 years, 1 month ago

CBSE > Class 12 > Biology

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How we identify the nightblindness

Posted by Sahil Enterprises 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Vibhav Tiwari 7 years, 1 month ago

People with night blindness experience poor vision at night or in dimly lit environments. Although the term “night blindness” implies that you can’t see at night, this isn’t the case. You may just have more difficulty seeing or driving in darkness.You’re more likely to experience night blindness when your eyes transition from a bright environment to an area of low light, such as when you leave a sunny sidewalk to enter a dimly lit restaurant. You’re likely to experience poor vision when driving due to the intermittent brightness of headlights and streetlights on the road. 3 possible conditions for night blindness 1 Cataract A cataract is a dense, cloudy area that forms in the lens of the eye. It develops slowly and eventually interferes with your vision. 2 Diabetic Retinopathy Diabetic retinopathy is a serious eye condition that can lead to decreased eyesight, or even blindness. Read about the causes and treatment options. 3 Abetalipoproteinemia Abetalipoproteinemia (ABL) is an inherited condition that prevents the body from completely absorbing certain dietary fats.

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Which of the chromosomes has max and lest no. Of genes?

Posted by Harmeet Singh 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Priyanshu Gupta 7 years, 1 month ago

Chr1and chrY respectively

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Features of ascaries,ovum,blastula,ameoba please help me

Posted by Abbas Shabbar 7 years, 1 month ago

CBSE > Class 12 > Biology

2 answers

Anki Kaushik 7 years, 1 month ago

Blastula- It is a 32 celled stage of embryonic development. It consist of trophoblast, inner cell mass and a cavity called blastocoel. Ascaris lumbricoides disease caused Ascariasis Symptoms of disease Constioation, Diarrhoea, anaemia. The patient turn anaemic and pale and shows weakness.

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Tilak Raj Sharma 7 years, 1 month ago

spooting experiments ??

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Example of cleistogamous flower

Posted by Puja Rani 7 years, 1 month ago

CBSE > Class 12 > Biology

3 answers

Priyanshu Mishra 7 years, 1 month ago

Oxalis is the flower which shows cleistogamous

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C Chauhan 7 years, 1 month ago

Pansy &viola

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Hema Bisht 7 years, 1 month ago

Is this a flower

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Which part of poppy plant is used to obtain the drug "smack"? Give reason plz. Answer

Posted by Abhishek Rai 7 years, 1 month ago

CBSE > Class 12 > Biology

0 answers

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Diagram of mature embryo sac

Posted by Gurudhyan Singh 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Gaurav Seth 7 years, 1 month ago

Refer to the attachmennt of Diagram of a mature embryo sac

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is fertilization involved in formation of false fruit ??

Posted by Jagdeep Kaur 7 years, 1 month ago

CBSE > Class 12 > Biology

5 answers

Lavesh Bohra 7 years, 1 month ago

No Because fruit is formed by ovary and due to fertilization embryo and zygote are formed not fruit

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Priyanshu Gupta 7 years, 1 month ago

Apple is a false fruit but developed after Fertillisation

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Priyanshu Gupta 7 years, 1 month ago

Fertillisation not occus in parthenocarpic fruits

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Priyanshu Gupta 7 years, 1 month ago

Yes

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Somyabrata Mohanty 7 years, 1 month ago

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biology practical textbook

Posted by Biprojit Das 7 years, 1 month ago

CBSE > Class 12 > Biology

0 answers

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Why tapetum cells become binucleated?

Posted by Anmol Sachdev 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Priyanshu Gupta 7 years, 1 month ago

Due to kariokinesis caried without cytokinesis

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One chromosome contains one molecule of DNA in Eukaryotic the length of the DNA molecule in enormous large explain how such a long molecule fits into the tiny chromosome seen at metaphase explain

Posted by Harman Singh 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Priyanshu Gupta 7 years, 1 month ago

With the help of histone and non histonal additional protein

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Clone

Posted by Nitin Raj 7 years, 1 month ago

CBSE > Class 12 > Biology

2 answers

Silent Punk 7 years, 1 month ago

Offspring which are morphologically and genetically similar are called clone.

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Priyanshu Gupta 7 years, 1 month ago

Copy of an organism with is genetically similar to it and phenotype is very much or totally similar

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Who discovered the blood circulation ?

Posted by Priyanshu Shahi 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Priyanshu Gupta 7 years, 1 month ago

William harwey

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What are split genes?

Posted by Shreya Sharma 7 years, 1 month ago

CBSE > Class 12 > Biology

0 answers

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Tell me some most imp daigrams for board exam 12 th class biology .if anybody know ..

Posted by Jitendra Jaiswal 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Meenu Yadav 7 years, 1 month ago

All diagrams are important especially of ecology -graphs, cycles, reproduction and molecular basis also

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Why do high altitude areas have brighter sunlight and lower temperatures as compared to the plains?

Posted by Brahmjot Kaur 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Arpan Basu Sachdeva 7 years, 1 month ago

At higher altitudes sunlight has to travel less distance in the atmosphere and scatters very less. Therefore sunlight is brighter there As you go upwards the air pressure decreases, hence temperature decreases on the fact that If vol. Is kept constant, temp. Is directly proportional to pressure(ex=pressure cooker)

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Herbivores are the predators of plants.write any 3 defence mechanism of plants against herbivory

Posted by Lakshmi Deva 7 years, 1 month ago

CBSE > Class 12 > Biology

3 answers

Brahmjot Kaur 7 years, 1 month ago

Plants have evolved various defences against herbivores such as :- 1. Thorns of Acacia and cactus are the most common morphological means of defence. 2. Some plants produce highly poisonous chemicals like cardiac glycosides, eg. weed Calatropis that makes the herbivore sick, etc. 3. Chemicals like nicotine, caffeine, quinine, strychnine, opium, etc., are actually defence mechanisms against grazers and browsers.

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Lakshmi Deva 7 years, 1 month ago

1.2 sharp thorns in acacia to deter herbivores. 1.3 In some plants,the margins if their leaves are spiny or have sharp edges that prevents herbivores. (2) chemical defence 2.1 chemical substances such as nicotine, caffeine, quinine,and opium are produced in plants as a defence. 2.2 All parts of calotropis weeds contain toxic cardiac glycosides,which can prove to be fatal if ingested by herbivores.

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Lakshmi Deva 7 years, 1 month ago

(1) Morphological defence mechanism: 1.1 cactus leaves are modified into sharp spines to deter herbivores from feeding on them

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What is polar vector

Posted by T S 7 years, 1 month ago

CBSE > Class 12 > Biology

0 answers

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Explain antihestamine?

Posted by Ahmed Raza 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Aakash Panchal 7 years, 1 month ago

Drugs which interfere with the natural action of histamine by competing with it binding sites of receptor where histamine exerts its effect are called antihistamines

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Explain translation?

Posted by Mansi Sharma 7 years, 1 month ago

CBSE > Class 12 > Biology

2 answers

Anu Anu 7 years, 1 month ago

It is defined as the process of polymerisation of amino acids to form a polypeptide. DNA to RNA process is called Transcription

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Abhishek Bonal 7 years, 1 month ago

The process synthesis of RNA from DNA this RNA is formation is complex

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What is polar vector?

Posted by T S 7 years, 1 month ago

CBSE > Class 12 > Biology

0 answers

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Diagram of transcription unit and function of each unit?

Posted by Anmol Bhatti 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Meghna Thapar 5 years, 8 months ago

Transcription Unit: The segment of DNA that takes part in transcription is called transcription unit. It has three components (i) a promoter, (ii) the structural gene and (iii) a terminator. Eukaryotes also require an enhancer.

The regions of the transcription unit with their functions are given below -

1. Promoter - The RNA Polymerase enzyme attaches in this region for starting the process of transcription.

2. Structural Gene - The enzymes and some proteins are coded by this site.

3. Terminator - It is responsible for ending the transcription process.

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Mode of asexual reproduction

Posted by Sonam Lilhare 7 years, 1 month ago

CBSE > Class 12 > Biology

1 answers

Yogita Ingle 7 years, 1 month ago

Asexual reproduction can occur in various modes. These are discussed below.

Binary Fission: One of the modes of asexual reproduction is binary fission. Mostly seen in single-celled organisms, the cell divides into two halves. Each half grows at a rapid pace to become an adult. Examples are Amoeba, Paramecium.
Fragmentation: In some multicellular organisms such as Spirogyra, asexual reproduction occurs through fragmentation. Here, the parent body divides fragments, which develops into a new individual.
Budding: Some organisms reproduce by budding, where buds develop on the parent body. Each new bud develops into a new organism. Example for this is Hydra.
Sporogenesis: Some organisms produce reproductive cells called spores. These spores grow into new organisms. The spores can spread through wind or through other animals.
Vegetative Propagation: This form of asexual reproduction is generally seen in plants, where a plant can grow a shoot. This shoot, in turn, has the ability to grow into a new organism.