Description : DIFFERENTIATE BETWEEN MORULA AND BLASTULA STAGES OF MAMMALIAN EMBRYO.
Last Answer : ANS. MORULA: (i) 8 TO 16 CELLED STAGE EMBRYO (ii) SOLID WITHOUT ANY CAVITY BLASTULA: (i) 32 CELLED STAGE EMBRYO. (ii) HOLLOW WITH A CAVITY CALLED BLASTOCOEL
Description : (i)Explain the events taking place at the time of fertilisation of an ovum in a human female. (ii)Trace the development of the zygote up to its implantation in the uterus. (iii)Name and draw a labelled sectional view of the embryonic stage that gets implanted. -Biology
Last Answer : (i)In humans, the fertilisation of ovum takes place in ampullary-isthmic junction of Fallopian tube. The events that occur during the process of fertilisation are: (a) The sperm reaches the ... endometrium of the uterus. This is called implantation.(iii) Blastocyst stage implants in the uterus.
Description : DESCRIBE THE PROCESS OF OOGENESIS IN HUMAN FEMALE AND DIFFERENTIATE IT WITH SPERMATOGENESIS ON THE BASIS OF TIME OF INITIATION AND THE PRODUCTS FORMED.
Last Answer : ANS. OOGENESIS : DIAGRAMMATIC REPRESENTATION AS GIVEN IN NCERT. DIFFERENCES BETWEEN : OOGENESIS SPERMATOGENESIS (i) STARTS DURING FOETAL LIFE (i) STARTS DURING PUBERTY (ii)PRODUCTS: OVUM (ii) SPERMS
Description : (a) IN WHICH PART OF HUMAN FEMALE REPRODUCTIVE SYSTEM DO THE FOLLOWING EVENTS TAKE PLACE. (i) RELEASE OF FIRST POLAR BODY (ii) RELEASE OF SECOND POLAR BODY (iii) FERTILISATION (iv) IMPLANTATION (b) NAME TWO HORMONES SECREATED ONLY DURING PREGNANCY.
Last Answer : ANS (a) (i) OVARY (ii) FALLOPIAN TUBE (iii) AMPULLA-ISTHAMUS JUNCTION OF FALLOPIAN TUBE (iv) ENDOMETRIUM LINING OF UTERUS (b) HUMAN CHORIONIC GONADOTROPIN AND HUMAN PLACENTAL LACTOGEN
Description : WHAT IS APOMIXIS? DESCRIBE ITS IMPORTANCE?
Last Answer : ANS. IT IS THE PROCESS OF DEVELOPMENT OF SEEDS WITHOUT FERTILISATION. EXAMPLE: SOME SPECIES OF ASTERACEAE AND GRASSES. IMPORTANCE: APOMICTIC GENES CAN BE INTRDUED IN HYBRID SEED INDUSTRY.
Description : (A) MENTION ANY FOUR STRATEGIES ADOPTED BY FLOWERING PLANTS TO PREVENT SELF-POLLINATION. (B) DEFINE THE TERM EMASCULATION.
Last Answer : ANS.(a) (i) SELF INCOMPATIBILITY (ii) PRODUCTION OF UNICELLULAR FLOWERS (iii) ANTHERS AND STIGMA ARE PLACED AT DIFFERENT POSITIONS. (iv) MATURATION OF ANTHER AND STIGMA IS NOT ... EMASCULATION: REMOVAL OF ANTHER BEFORE MATURITY SO AS TO ENSURE CROSS POLLINATION IN SELF POLLINATING FLOWERS.
Description : DESCRIBE THE CONTRACEPTIVE ACTIONS OF IUDs.
Last Answer : ANS. (i) INCREASES PHAGOCYTOSIS OF SPERMS (ii) SUPPRESS SPERM MOTILITY (iii) SUPPRESS FERTILISING CAPACITY OF SPERMS (iv) MAKES CERVIX HOSTILE TO SPERMS.
Description : WHAT IS CORPUS LUTEUM ? UNDER WHAT CONDITIONS DOES IT UNDERGO DEGENERATION ?
Last Answer : ANS. THE CORPUS LUTEUM IS FORMED IN THE MAMMALIAN OVARY FROM RUPTURED GRAAFIAN FOLLICLE AFTER OVULATION. IT DEGENERATES IN THE ABSENCE OF FERTILISATION, AS THE LEVEL OF FSH AND LH DROPS.
Description : WRITE THE FUNTION OF EACH OF THE FOLLOWING: (a) MIDDLE PIECE OF HUMAN SPERM (b) LUTEINIZING HORMONE IN HUMAN MALES
Last Answer : ANS. (a) PROVIDES ENERGY FOR MOVEMENT DUE TO PRESENCE OF MITOCHONDRIA. (c) STIMULATES SYNTHESIS AND SECRETION OF ANDROGENS.
Description : STATE ONE ADVANTAGE AND ONE DISADVANTAGE OF CLEISTOGAMY.
Last Answer : ANS. ADVANTAGE: ASSURED SEED SET DISADVANTAGE: INBREEDING DEPRESSION.
Description : WHY IS THE PROCESS OF FERTILISATION IN A FLOWERING PLANT REFFERED TO AS DOUBLE FERTILISATION ?
Last Answer : ANS. DOUBLE FERTILISATION= SYNGAMY + TRIPLE FUSION SYNGAMY= ONE MALE GAMETE + EGG--- ZYGOTE(n) TRIPLE FUSION= ANOTHER MALE GAMETE+ POLAR NUCLEI-PRIMARY ENOSPERM NUCLEUS(3n)
Description : WHEN DO THE OOGENESIS AND THE SPERMATOGENESIS INITIATE IN HUMAN FEMALES AND MALES RESPECTIVELY ?
Last Answer : ANS. OOGENESIS AT THE FOETAL LIFEAND SPERMATOGENISIS STARTS AT PUBERTY.
Description : WRITE THE LOCATION AND FUNCTION OF SERTOLI CELLS IN HUMANS.
Last Answer : ANS. IN THE SEMINIFEROUS TUBULES OF TESTIS, NOURISHES DEVELOPING SPERMS.
Description : NAME THE PROTECTIVE SUBSTANCE PRESENT IN THE POLLEN ENVELOPE TO TIDE OVER ADVERSE CONDITIONS.
Last Answer : ANS. SPOROPOLLENIN.
Description : NAME THE TYPE OF FLOWER WHICH FAVOURS CROSS POLLINATION.
Last Answer : ANS. CHASMOGAMOUS.
Description : WHAT IS PERISPERM ?
Last Answer : ANS. THE RESIDUAL NUCELLUS, WHICH PERSISTS IN THE SEEDS IS CALLED AS PERISPERM.
Description : NAME THE PHENOMENON AND ONE BIRD WHERE THE FEMALE GAMETE DIRECTLY DEVELOPS INTO A NEW ORGANISM.
Last Answer : ANS. PARTHENOGENESIS, TURKEY.
Description : WHY ARE DATE PALMS REFFERED TO AS DIOECIOUS ?
Last Answer : ANS. BECAUSE THEY HAVE UNISEXUAL FLOWERS BORNE ON SEPARATE PLANTS.
Description : WHAT TERM IS GIVEN BY YOU TO THE GROUP OF INDIVIDUALS WHICH ARE GENETICALLY AND MORPHOLOGICALLY IDENTICAL ?
Last Answer : ANS. CLONE
Description : Test tube baby means a baby born when (a) it is developed in a test tube (b) it is developed through tissue culture method (c) the ovum is fertilised externally and thereafter implanted in the uterus (d) it develops from a non-fertilised uterus.
Last Answer : (c) the ovum is fertilised externally and thereafter implanted in the uterus
Description : The contraceptive ‘Saheli’ (a) blocks estrogen receptors in the uterus, preventing eggs from getting implanted (b) increases the concentration of estrogen and prevents ovulation in females (c) is an IUD (d) is a post-coital contraceptive.
Last Answer : (a) blocks estrogen receptors in the uterus, preventing eggs from getting implanted
Description : In human female, the blastocyst (a) forms placenta even before implantation (b) gets implanted into uterus 3 days after ovulation (c) gets nutrition from uterine endometrial secretion only after implantation (d) gets implanted in endometrium by the trophoblast cells.
Last Answer : (d) gets implanted in endometrium by the trophoblast cells.
Description : The contraceptive 'SAHELI' (1) blocks estrogen receptors in the uterus, preventing eggs from getting implanted. (2) increases the concentration of estrogen and prevents ovulation in females. (3) is an lUD. (4) is a post-coital contraceptive.
Last Answer : (1) blocks estrogen receptors in the uterus, preventing eggs from getting implanted.
Description : Study the given figure below and answer the question that follow important-questions-for-class-12-biology-cbse-fertilisation-pregnancy-and-embryonic-development-t-33-3 (i)Name the stage of human embryo the ... implantation in the uterus. (iv)Where are the stem cells located in this embryo? -Biology
Last Answer : (i)The stage is blastocyst. (ii) A—Trophoblast. It helps in attachment to endometrium during implantation and provides nourishment to developing embryo. (iii) Inner cell mass acts as precursor to embryo ... into ectoderm and endoderm. (iv) Stem cells are located in inner cell mass of embryo.
Description : The stage transferred into the uterus after induced fertilisation of ovum in the laboratory is (a) embryo at 4 blastomeres stage (b) embryo at 2 blastomeres stage (c) morula (d) zygote.
Last Answer : (c) morula
Description : Name the embryonic stage that gets implanted in the uterine wall of a human female. -Biology
Last Answer : Blastocyst gets implanted in the uterine wall.
Description : In cloning of cattle a fertilized egg is taken out of the mother's womb and (a) in the eight cell stage, cells are separated and cultured until small embryos are formed which are implanted into the ... d) the egg is divided into 4 pairs of cells which are implanted into the womb of other cows.
Last Answer : (a) in the eight cell stage, cells are separated and cultured until small embryos are formed which are implanted into the womb of other cows
Description : In mammalian embryo the pulmonary aorta communicates with carotico-systemic aorta by a narrow ductus arteriosus, in the adult this connection closes l
Last Answer : In mammalian embryo the pulmonary aorta communicates with carotico-systemic aorta by a narrow ductus ... C. Ligamentum arteriosus D. None of these
Description : Excretory products of mammalian embryo are eliminated out by - (1) Placenta (2) Amniotic fluid (3) Allantois (4) Ureter
Last Answer : (1) Placenta Explanation: The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood ... are also found in some snakes and lizards with yawing levels of development up to mammalian levels.
Description : The extra embryonic membranes of the mammalian embryo are derived from (a) trophoblast (b) inner cell mass (c) formative cells (d) follicle cells
Last Answer : (a) trophoblast
Description : The amnion of mammalian embryo is derived from (a) ectoderm and mesoderm (b) endoderm and mesoderm (c) mesoderm and trophoblast (d) ectoderm and endoderm
Last Answer : (a) ectoderm and mesoderm
Description : The amnion of mammalian embryo is derived from (1) ectoderm and mesoderm (2) endoderm and mesoderm (3) mesoderm and trophoblast (4) ectoderm and endoderm
Last Answer : (1) ectoderm and mesoderm
Description : Excretory products of mammalian embryo are eliminated out by (1) Placenta (2) Amniotic fluid (3) Allantois (4) Ureter
Last Answer : Placenta
Description : Which extra-embryonic membrane in human prvents desiccation of the embryo inside the uterus?
Last Answer : Which extra-embryonic membrane in human prvents desiccation of the embryo inside the uterus? A. Yolk one B. Amnion C. Chorion D. Allantois.
Last Answer : Which extra-embryonic membrane in human prvents desiccation of the embryo inside the uterus? A. Yolk sac B. Amnion C. Chorion D. Allantois
Description : The term Test Tube Baby' implies (a) Fertilisation of ovum takes place I the test tube but it develops in uterus (b) Fertilisation of ovum takes place in the test tube and develops in ... uterus but develops in the test tube (d) Fertilisation takes place in uterus and embryo develops in uterus
Last Answer : Ans:(a)
Description : In the case of test tube babies (1) egg is fertilized in the uterus. (2) embryo completes its development in a test tube. (3) embryo is placed in uterus after 2 months. (4) egg is fertilized outside mother's body.
Last Answer : (3) embryo is placed in uterus after 2 months. Explanation: Prior of the implantation of the blastocyst the uterus of the recipient mother should be made ready to receive the embryo. This is ... done with the hormonal treatment. The blastocyst is introduced into the uterus by one of the two methods
Description : A test tube baby means : (1) a baby grown in a test tube. (2) embryo fertilised in uterus and developed in test tube. (3) embryo fertilised and developed in uterus. (4) fertilisation in vitro and then transplantation in the uterus.
Last Answer : (4) fertilisation in vitro and then transplantation in the uterus. Explanation: In vitro fertilisation is a process by which an egg is fertilised by sperm outside the body: in vitro. IVF is a ... to collect a naturally selected ovum (egg) for fertilisation, it is known as natural cycle IVF.
Description : Name the organ where the embryo develops - (1) Uterus (2) Fallopian tube (3) Ureter (4) Cervix
Last Answer : (3) Uterus Explanation: In a placental mammal, an ovam is fertilized in a fallopian tube through which it travels into the uterus.
Description : The test tube baby means (a) fertilisation and development both in uterus (b) fertilisation in vitro and then transplantation in uterus (c) a baby grown in test tube (d) fertilised and developed embryo in test tube.
Last Answer : (b) fertilisation in vitro and then transplantation in uterus
Description : Assisted reproductive technology, IVF involves transfer of (a) ovum into the fallopian tube (b) zygote into the fallopian tube (c) zygote into the uterus (d) embryo with 16 blastomeres into the fallopian tube.
Last Answer : b) zygote into the fallopian tube
Description : Embryo with more than 16 blastomeres formed due to in vitro fertilisation is transferred into (a) uterus (b) fallopian tube (c) fimbriae (d) cervix.
Last Answer : (a) uterus
Description : The permissible use of the technique amniocentesis is for (a) detecting sex of the unborn fetus (b) artificial insemination (c) transfer of embryo into the uterus of a surrogate mother (d) detecting any genetic abnormality.
Last Answer : (d) detecting any genetic abnormality.
Description : Which extraembryonic membrane in humans prevents desiccation of the embryo inside the uterus? (a) Yolk sac (b) Amnion (c) Chorion (d) Allantosis
Last Answer : (b) Amnion
Description : Ectopic pregnancies are referred to as (a) implantation of defective embryo in the uterus (b) pregnancies terminated due to hormonal imbalance (c) pregnancies with genetic abnormality (d) implantation of embryo at site other than uterus.
Last Answer : (d) implantation of embryo at site other than uterus.
Description : Given below are the events that lead to pregnancy and development of embryo i. fertilisation of egg ii. maturation of egg iii. release of egg iv. embedding of embryo in uterus a) i, ii, iii, iv b)ii, i, iii, iv c)i, iv , ii, iii d)ii, iii, i , iv,
Last Answer : d)ii, iii, i , iv,
Description : In human beings after fertilisation , the structure which gets embedded in the wall of uterus is a) ovum b)embryo c)foetus d)zygote
Last Answer : b)embryo
Description : 3. In IVF technique zygote or early embryo is transferred into a. Cervical canal b. Uterus c. Fallopian tube d. Vagina
Last Answer : c. Fallopian tube
Description : In a normal pregnant woman, the amount of total gonadotropin activity was assessed. The result expected was (1) High level of circulating HCG to stimulate estrogen and progesterone synthesis (2) ... endometrial thickening (4) High levels of FSH and LH in uterus to stimulate endometrial thickening
Last Answer : (1) High level of circulating HCG to stimulate estrogen and progesterone synthesis
Description : The placenta in humans is derived from the: a) embryo only b) uterus only c) endometrium and embryo d) none of the above
Last Answer : ANSWER: C -- ENDOMETRIUM AND EMBRYO