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 A normal couple gave birth to one heamophillic son and two normal daughter work out the cross to show the genotypes of the parent and thier progeny?? 

Posted by ayan siddiqui (Jun 18, 2017 1:24 p.m.) (Question ID: 5996)

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Why some seeds referred as apomitic seeds ?Mention one advantage and disadvantage to a farmer who uses them

Posted by Puneet solanki (Jun 16, 2017 5:16 p.m.) (Question ID: 5943)

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What is the cause of down's syndrome in humans?

Posted by Ritika kohli (Jun 13, 2017 9:01 p.m.) (Question ID: 5896)

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  • The most common form of Down syndrome is known as trisomy 21, a condition where individuals have 47 chromosomes in each cell instead of 46. Trisomy 21 is caused by an error in cell division called nondisjunction, which leaves a sperm or egg cell with an extra copy of chromosome 21 before or at conception

    Answered by Payal Singh (Jun 13, 2017 10:37 p.m.)
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Difference between hemophilia and thalassemia 

Posted by mamta vaish (Jun 09, 2017 9:22 a.m.) (Question ID: 5782)

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  • Ans. Haemophilia is the deficiency of blood.During Haemophilia you have a low platelets count and bleed very easily and don't clot that well. Haemophilia is either hereditary or caused by a spontaneous mutation.

    Thalassaemia is the name of a group of genetic, inherited disorders of the blood. More specifically, it is a disorder of the haemoglobin molecule inside the red blood cells. It is an inherited genetic disease i.e. a disease that is passed from parents to children through the genes (genetic).

    Answered by Naveen Sharma (Jun 09, 2017 3:28 p.m.)
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Cause of hemophilia and thalassemia 

 

Posted by mamta vaish (Jun 09, 2017 8:29 a.m.) (Question ID: 5781)

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  • Hi,

    Haemophilia is a X-linked recessive genetic disorder that impairs the body’s ability to coagulate or clot blood when a blood vessel breaks.This disorder occurs when a single factor from the several factors required for the process of coagulation is affected. Hemophilia A is caused by a mutation in the gene for factor VIII, so there is deficiency of this clotting factor.Hemophilia B (also called Christmas disease) results from a deficiency of factor IX due to a mutation in the corresponding gene.It is a sex-linked recessive disorder inherited through the X-chromosome. The possibility of a male offspring inheriting this disorder is greater than in females

     

    Thalassemia is an autosomal recessive disorder whcih affects the blood. Haemoglobin synthesised by the body is abnormal and is unable to carry oxygen efficiently. this later leads to the destruction of blood cells and thereby causes anemia.Thalassemia develops when there is some abnormality in any one of the genes that are involved in the production of hemoglobin and this defect can be inherited from your parents.

    Thalassemia disease exists in two forms namely:

    Alpha-thalassemia – At least one of the alpha globin genes has an abnormality or mutation.

    Beta-thalassemia – The beta globin genes are infected.

    Hope this will help you out ..!!

    Answered by Swati Sohni (Jun 09, 2017 9:04 a.m.)
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Why is there fear amongst the guardians that their adolescents wards may get trapped in drug/alcohol abuse. 

Posted by mamta vaish (Jun 09, 2017 8:12 a.m.) (Question ID: 5780)

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  • There is a fear amongst the guardians that their adolescents wards may get trapped in drug/alcohol abuse, due to the detrimental effects of abusing drugs.

     Effects of drug/alcohol abuse – 

    • Reckless behaviour
    • Malicious mischief
    • Violence
    • Drop in academic performance
    • Depression, isolation, aggressiveness, etc.

    and the possible reason for  drug abuse – 

    • Curiosity
    • Adventure
    • Excitement
    • Experimentation
    • Stress or pressure to excel in examination

     

    Hope this will help you out ..!!

     

    Answered by Swati Sohni (Jun 09, 2017 9:10 a.m.)
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A proper understanding of menstrual cycle can help immensely in family planning. Do you agree. Provide reasons for your answer. 

Posted by mamta vaish (Jun 09, 2017 7:45 a.m.) (Question ID: 5779)

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  • Yes, a proper understanding of menstrual cycle can help immensely in family planning. As day 10 to 17 of the menstrual cycle is called as FERTILE PERIOD of human female. If coitus done during this period increases the chances of conception but coitus is abstained in this period, pregnancy can be prevented.

    Answered by Swati Sohni (Jun 09, 2017 9:12 a.m.)
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When a seed of An orange is squeezed,many embryos, instead of one are observed. Explain how it is possible. 

Posted by mamta vaish (Jun 09, 2017 7:27 a.m.) (Question ID: 5778)

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  • Some of the nuclear cells surrounding embryonic sac start to divide an protrude inside the embryonic sack and forms embryo.

    Occurrence of more than embryo in a seed is called as polyembryony, as in orange.

    Answered by Payal Singh (Jun 09, 2017 11:02 a.m.)
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(a)-When a seed of An orange is squeezed, many embryos, instead of one are observed. Explain how it is possible.       (b) - Are these embryos genetically similar or different. Comment. 

Posted by mamta vaish (Jun 09, 2017 7:03 a.m.) (Question ID: 5777)

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  • Some of the nuclear cells surrounding embryonic sac start to divide an protrude inside the embryonic sack and forms embryo.

    Occurrence of more than embryo in a seed is called as polyembryony, as in orange.

    Answered by Payal Singh (Jun 09, 2017 11:02 a.m.)
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State the Mendes's law of inheritance that is universally accepted. 

Posted by mamta vaish (Jun 09, 2017 6:31 a.m.) (Question ID: 5776)

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  • Law of segregation is universally accepted with no exception. Law of segregation states that each trait is consist of two alleles, which get segregate during the formation of gametes and one allele from each parent combine during fertilization.

    Answered by Payal Singh (Jun 09, 2017 6:54 a.m.)
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To estimate  the amount of fats in different dry fruits

Posted by Amir Khan (Jun 02, 2017 9:11 a.m.) (Question ID: 5629)

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  • Dear Students,

    Plz go through this link, hope it will help you in estimating fat content .

    http://district.schoolnutritionandfitness.com/visaliausd/files/SB12Howtocalculatefat.pdf 

    Answered by Swati Sohni (Jun 09, 2017 11:05 a.m.)
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What is the difference between secondary oocyte and tertiary oocyte??

Posted by Sushma priyam (May 31, 2017 5:54 p.m.) (Question ID: 5601)

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  • Primary oocyte is a diploid cell formed in foetal ovary when the gamete mother cell, oogonia is arrested at prophase-I of meiosis. Secondary oocyte is the haploid cell formed from primary oocyte that completes its first meiotic division, during puberty and produces the female gamete ova.

    Answered by Payal Singh (May 31, 2017 6:33 p.m.)
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what is the difference between syngamy and fertilisation ?

Posted by chetna singh (May 30, 2017 7:17 a.m.) (Question ID: 5570)

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  • Dear Chetna ,

    Syngamy means union of the male and female pro nuclei a step that happens after fertilization.

    Fertilization means penetration of the sperm head into the zona pellucida layer of the egg and discharge of sperm pro nucleus into the egg.

    I hope it will help you out ..

    Answered by Swati Sohni (Jun 07, 2017 12:12 p.m.)
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  • Syngamy and fertilization are synonyms just the diffrerence between them is that syngamy is the process of fusion of two gametes to form zygote while fertilisation refers to the act or process of rendering fertile.

    Answered by Payal Singh (May 30, 2017 7:32 a.m.)
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I pass 12th this year with five subject but fail in bio what should i do please help

Posted by Devesh Shukla (May 29, 2017 11:15 a.m.) (Question ID: 5554)

  • u help ncer  and s chandra and cleared of all Q

    Posted by gaurav shukla (May 30, 2017 8:18 a.m.)
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  • Dear Devesh ,

    Focus on 3 marks and 5 marks question from CBSE previous papers ( last 5 years)and do not rely on sample and model test paper.

    Answered by Swati Sohni (Jun 09, 2017 11:04 a.m.)
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Is a haploid organisms life cycle ?where does the meisos take pa
place?

Posted by Janvi patiyal (May 28, 2017 10:57 a.m.) (Question ID: 5533)

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  • Usually the in the life cycle of a haploid organism meiosis doesn't take place but in some of the fungi and algae have a temporary diploid stage in their life cycle from the fusion of two cells arisen due to mitosis. This fused cells are diploid which then undergo meiosis. The end result of this process is a spore.

    Answered by Amrita Mukherjee (May 30, 2017 5:37 p.m.)
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why both the sexes are present in some individual ?

Posted by Janvi patiyal (May 28, 2017 10:55 a.m.) (Question ID: 5532)

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  • This situation may arise due to unusual sex hormones. The unusual hormones may be caused by an atypical set of sex chromosomes. Upon fertilization of the two ova by two sperm cells carrying 'X' and 'Y' respectively, the two fertilized ova are then fused together resulting in individual having dual genitalia, gonads and genetic sex.

    Another common cause of being intersex is the crossing over of SRY region from 'Y' chromosome to the 'X' during meiosis. The SRY is then activated in only certain areas causing development of testes and in other areas not being active causing the growth of ovarian tissue.

    Thus testicular and ovarian tissues can be present in same individual.

    Answered by Amrita Mukherjee (May 30, 2017 6:01 p.m.)
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What can be the examples of orchid fruits ?

Posted by Deepika Gaur (May 28, 2017 10:17 a.m.) (Question ID: 5530)

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  • Dear Deepika,

    Vanilla planifolia is the source of vanilla, one of the most popular flavours in the world, and weight for weight, one of the most valuable spice crops.

    The vanilla orchid Vanilla planifolia grows wild in tropical forests in Central America. It belongs to one of the largest families of flowering plants – the orchids (Orchidaceae). Vanillas (members of the Vanilla genus) are the only orchids that produce an agriculturally valuable crop, and 95% of the world’s traded vanilla pods are derived from just one species – V. planifolia.

     

    I hope it will help you out ..

    Answered by Swati Sohni (Jun 07, 2017 11:40 a.m.)
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What is gestation?

Posted by SJ Jinsey (May 24, 2017 12:23 p.m.) (Question ID: 5461)

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  • Gestation is the process of development of fetus, beginning with fertilization and ending at birth. The duration of gestation period varies between species.

    Answered by Payal Singh (May 24, 2017 12:38 p.m.)
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Why sexual reproduction is considered as unfavourable mode of reproduction

 

Posted by Jaiprakash Lackrany (May 12, 2017 4:12 p.m.) (Question ID: 5257)

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An other name of heterogamete as homogamete is isogametes

Posted by Anamika pal (May 12, 2017 11:44 a.m.) (Question ID: 5251)

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  • Another name of homogamete is isogamous

     

    Answered by Jaiprakash Lackrany (May 12, 2017 4:14 p.m.)
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  • An other name of heterogametes is anisogametes

    Answered by Payal Singh (May 12, 2017 12:01 p.m.)
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What happens in oestrous cycle

Posted by Anamika pal (May 12, 2017 11:42 a.m.) (Question ID: 5250)

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  • Ans. Oestrous is the main reproductive cycle of other species females of non-primate vertebrates, for example rats, mice, horses, pig have this form of reproductive cycle.
     

    Estrous Cycle Stages:  
    proestrus - estrus - metestrus - diestrus

    • Proestrus:The first stage in the estrous cycle immediately before estrus characterized by development of both the endometrium and ovarian follicles.
    • Estrus: The second stage in the estrous cycle immediately before metestrus characterized by a receptivity to a male and to mating, often referred to as "heat" or "in heat". Pheromones may also be secreted only at this stage of her cycle.
    • Metestrus The third stage in the estrous cycle immediately before diestrus characterized by sexual inactivity and the formation of the corpus luteum.
    • Diestrus The last stage in the estrous cycle immediately before the next cycle proestrus characterized by a functional corpus luteum and an increase in the blood concentration of progesterone.
    Answered by Naveen Sharma (May 12, 2017 12:11 p.m.)
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What are pseudopodiospores

Posted by Anamika pal (May 12, 2017 11:41 a.m.) (Question ID: 5249)

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  • Pseudopodiospores are spores produced by the amoeba under favorable condition to carry out asexual reproduction means producing new amoeba from each pseudopodiospore.

    Answered by Payal Singh (May 12, 2017 12:02 p.m.)
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Which type of reproduction take place in onion

 

 

Posted by Anamika pal (May 12, 2017 11:39 a.m.) (Question ID: 5248)

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  • Ans. Onions reproduce either with seeds or by bulbils (little bulbs) that form from lateral buds.

    Answered by Naveen Sharma (May 12, 2017 12:06 p.m.)
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the part of fallopian tube closest to ovary is .......

Posted by Raima Rakshit (May 05, 2017 9:04 p.m.) (Question ID: 5127)

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  • The fimbriae region of infundibulum is closest to ovary.

    Answered by Swati Sohni (Jun 07, 2017 11:54 a.m.)
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  • no its infundibulum  the ans....

    Answered by Aashka Shah (May 09, 2017 2:40 p.m.)
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  • so what about infundibulum of fallopian tube 

     

    Answered by Raima Rakshit (May 06, 2017 11:44 a.m.)
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  • The part of fallopian tube closest to ovary is Ampulla.

    Answered by Payal Singh (May 06, 2017 7:51 a.m.)
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What is species diversity?

Posted by Pallavi Kapoor (May 02, 2017 5:59 p.m.) (Question ID: 5085)

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  • Species diversity is defined as the number of species and abundance of each species that live in a particular location.

    The number of species that live in a particular location is called species richness.

    Abundance is defined as the number of individuals of each species.

    Answered by Payal Singh (May 03, 2017 7:02 a.m.)
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What is ecological diversity?

Posted by Pallavi Kapoor (May 01, 2017 9:14 p.m.) (Question ID: 5077)

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  • Ecological diversity is a type of biodiversity.

    It is the variation in the ecosystems found in a region or the variation in ecosystems over the whole planet.

    Ecological diversity includes the variation in both terrestrial and aquatic ecosystems.

    Answered by Payal Singh (May 02, 2017 12:22 p.m.)
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What is genetic diversity?

Posted by Pallavi Kapoor (May 01, 2017 9:13 p.m.) (Question ID: 5076)

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  • Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species.

    It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary.

    Genetic diversity serves as a way for populations to adapt to changing environments

    Answered by Payal Singh (May 02, 2017 12:20 p.m.)
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What is the significance of biodiversity?

Posted by Pallavi Kapoor (May 01, 2017 9:13 p.m.) (Question ID: 5075)

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  • Biodiversity is the sum total of different plants and animal species in a particular placenta particular time. It refers to the totality of genes, species and ecosystems of a region and it differs from place to place.

    Importance of Biodiversity:

    • All living organisms are required to keep the ecosystem alive.
    • One organism cannot exist without other organisms.
    • Biodiversity is important for survival of the human.
    • Plants are the producers by photosynthesis and transfer the diminished rate of energy from one tropic level to other.
    • Biodiversity has valuable genetic resources. Biodiversity plays an important role in breeding and improvement of species.
    • Rain forests and ponds contribute to natural water purification.
    • Biodiversity preserves the ecosystem.
    • Hence biodiversity is called as ‘balance of nature’ Biodiversity is a hidden treasure that enriches all our lives.
    Answered by Payal Singh (May 02, 2017 12:32 p.m.)
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What is the significance of variation?

Posted by Pallavi Kapoor (May 01, 2017 9:12 p.m.) (Question ID: 5074)

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  • In nature, variations occur during sexual reproduction. If this variation is beneficial to the species, it is selected and remains in the population. This is because the variant species are more adapted. Therefore, they can survive better and reproduce to pass the genes to the offsprings.

     

    Variations are very important for organisms to survive because if there were no variations among living organisms there would have been no evolution or change and natural conditions do not remain constant they keep on changing. If variations stops then we would not be able to adapt to the changing conditions and can prove catastrophic to us.

    Answered by Payal Singh (May 02, 2017 12:33 p.m.)
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What is the role of evolution in biodiversity?

Posted by Pallavi Kapoor (May 01, 2017 9:10 p.m.) (Question ID: 5073)

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