(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

(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
by

1 Answer

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 junction of ampulla and isthmus and comes in contact with zona pellucida layer of ovum. (b) Acrosome of sperm head release sperm lysin enzymes that dissolves corona radiata and digests zona pellucida layer and enters cytoplasm. (c) Entry of sperm stimulates secondary oocyte to complete its suspended second meiotic division, thus producing haploid egg or ovum and second polar body. (d)Nucleus of sperm and of ovum fuses to form a diploid zygote. (ii)Development of zygote up to implantation takes place in following sequenceCleavage division (mitotic) starts in zygote as it moves through the isthmus of Fallopian tube towards the uterus.This division results into 2, 4, 8 and 16 daughter cells called blastomeres.The embryo with 8-16 blastomeres is called morula.Morula continues to divide and transforms into blastocyst as it moves further into uterus.Blastomeres in the blastocyst are arranged into an outer layer called trophoblast and inner group of cells attached to trophoblast called inner cell mass.Trophoblast layer then gets attached to the endometrium and the inner cell mass gets differentiated as the embryo.After attachment, the uterine cells divide rapidly and cover the blastocyst. It leads to blastocyst’s embedding in the endometrium of the uterus. This is called implantation.(iii) Blastocyst stage implants in the uterus.
by

Related questions

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 figure represents. (ii)Identify Ain the figure and mention its function. (iii)Mention the fate of the inner cell mass after implantation in the uterus. (iv)Where are the stem cells located in this embryo? -Biology

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.

(i) Mention the event that induces the completion of the meiotic division of the secondary oocyte. (ii) Trace the journey of the ovum from the ovary, its fertilisation and further development until the implantation of the embryo. -Biology

Description : (i) Mention the event that induces the completion of the meiotic division of the secondary oocyte. (ii) Trace the journey of the ovum from the ovary, its fertilisation and further development until the implantation of the embryo. -Biology

Last Answer : (i)Secondary oocyte completes meiosis-ll only when a sperm enters its cytoplasm. It forms a larger cell, the ootid and a small cell, the second polar body. (ii)The secondary oocyte is ... and inner cell mass.The trophoblast attacheds to endometrium (implantation) and blastocyst gets embedded in it.

In human beings after fertilisation , the structure which gets embedded in the wall of uterus is a) ovum b)embryo c)foetus d)zygote

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

Describe the post-zygotic events leading to implantation and placenta formation in humans. Mention any two functions of placenta. [All India 2010] or Explain the process of fertilisation in human female and trace the post-fertilisation events in a sequential order up to implantation of the embryo. [Foreign 2010] -Biology

Description : Describe the post-zygotic events leading to implantation and placenta formation in humans. Mention any two functions of placenta. [All India 2010] or Explain the process of fertilisation in human female ... events in a sequential order up to implantation of the embryo. [Foreign 2010] -Biology

Last Answer : Post-zygotic events leading to implantation and placenta formation. After implantation of blastocyst, the finger-like projections called chorionic villi, appear on the trophoblast and is surrounded by ... acts as an endocrine gland and secretes hormones like hPL, hCG, oestrogen and progesterone.

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.

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.

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.

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

(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.

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

Name the embryonic stage that gets implanted in the uterine wall of a human female. -Biology

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.

Draw a diagrammatic sectional view of human ovary showing different stages of oogenesis along with corpus luteum. (ii) Where is morula formed in human? Explain the process of its development from zygote. -Biology

Description : Draw a diagrammatic sectional view of human ovary showing different stages of oogenesis along with corpus luteum. (ii) Where is morula formed in human? Explain the process of its development from zygote. -Biology

Last Answer : (i) Sectional view of human ovary. (ii) Morula is formed in the (a)Isthmus of the oviduct (Fallopiantube). (b)The zygote undergoes mitotic divisions in quick succession called cleavage, forming 2, 4 ... 8-16 blastomeres is called a morula and the inner cell mass gets ready to form the embryo proper.

The figure given below depicts a diagrammatic sectional view of the human female reproductive system. Which set of three parts out of I-VI have been correctly identified? I II III V VI IV (a) (II) Endometrium, (III) Infundibulum, (IV) Fimbriae (b) (III) Infundibulum, (IV) Fimbriae, (V) Cervix (c) (IV) Oviducal funnel, (V) Uterus, (VI) Cervix (d) (I) Perimetrium, (II) Myometrium, (III) Fallopian tube

Description : The figure given below depicts a diagrammatic sectional view of the human female reproductive system. Which set of three parts out of I-VI have been correctly identified? I II III V VI IV (a) (II) ... , (V) Uterus, (VI) Cervix (d) (I) Perimetrium, (II) Myometrium, (III) Fallopian tube

Last Answer : (b) (III) Infundibulum, (IV) Fimbriae, (V) Cervix

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,

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,

Which one of the following is the most likely root cause why menstruation is not taking place in regularly cycling human female? (a) Maintenance of the hypertrophical endometrial lining (b) Maintenance of high concentration of sex- hormones in the blood stream (c) Retention of well-developed corpus luteum (d) Fertilisation of the ovum

Description : Which one of the following is the most likely root cause why menstruation is not taking place in regularly cycling human female? (a) Maintenance of the hypertrophical endometrial lining (b) ... the blood stream (c) Retention of well-developed corpus luteum (d) Fertilisation of the ovum

Last Answer : (b) Maintenance of high concentration of sex- hormones in the blood stream

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.

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

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 the test tube itself (c) Fertilisation of the ovum takes place in the uterus but develops in the test tube (d) Fertilisation takes place in uterus and embryo develops in uterus

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)

(i) Draw a labelled diagram of the human female reproductive system. (ii) Enumerate the events in the ovary of a human female during (b) Luteal phase of menstrual cycle (a) Follicular phase -Biology

Description : (i) Draw a labelled diagram of the human female reproductive system. (ii) Enumerate the events in the ovary of a human female during (b) Luteal phase of menstrual cycle (a) Follicular phase -Biology

Last Answer : (i)Refer to page no. 43. (2) (ii) (a) Follicular phase The primary follicle in the ovary grow to become fully mature Graafian follicle. Endometrium gets thickened. The ... Luteal phase The remaining parts of ruptured Graafian follicle transforms into corpus luteum, that secretes progesterone.

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.

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

The technique called Gamete Intra Fallopian Transfer (GIFT) is recommended for those females (a) who cannot produce an ovum (b) who cannot retain the fetus inside uterus (c) whose cervical canal is too narrow to allow passage for the sperms (d) who cannot provide suitable environment for fertilisation.

Description : The technique called Gamete Intra Fallopian Transfer (GIFT) is recommended for those females (a) who cannot produce an ovum (b) who cannot retain the fetus inside uterus (c) whose cervical ... narrow to allow passage for the sperms (d) who cannot provide suitable environment for fertilisation.

Last Answer : (a) who cannot produce an ovum

Fertilisation in humans is practically feasible only if (a) the ovum and sperms are transported simultaneously to ampullary-isthmic junction of the cervix (b) the sperms are transported into cervix within 48 hrs of release of ovum in uterus (c) the sperms are transported into vagina just after the release of ovum in fallopian tube (d) the ovum and sperms are transported simultaneously to ampullary-isthmic junction of the fallopian tube.

Description : Fertilisation in humans is practically feasible only if (a) the ovum and sperms are transported simultaneously to ampullary-isthmic junction of the cervix (b) the sperms are transported ... the ovum and sperms are transported simultaneously to ampullary-isthmic junction of the fallopian tube.

Last Answer : (d) the ovum and sperms are transported simultaneously to ampullary-isthmic junction of the fallopian tube.

Explain the events that occur during fertilisation of an ovum in humans. How is it that only one sperm enters the OVUm? -Biology

Description : Explain the events that occur during fertilisation of an ovum in humans. How is it that only one sperm enters the OVUm? -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 ... that blocks the entry of additional sperms. This ensures that only one sperm can fertilise an ovum

AT WHAT STAGE IS THE MAMMALIAN EMBRYO IMPLANTED IN THE UTERUS ?

Description : AT WHAT STAGE IS THE MAMMALIAN EMBRYO IMPLANTED IN THE UTERUS ?

Last Answer : ANS. AT THE BLASTOCYST STAGE.

In human females, meiosis-II is not completed until (a) uterine implantation (b) birth (c) puberty (d) fertilisation.

Description : In human females, meiosis-II is not completed until (a) uterine implantation (b) birth (c) puberty (d) fertilisation.

Last Answer : (d) fertilisation.

In vitro fertilisation is a technique that involves transfer of which one of the following into the fallopian tube? (a) Embryo only, upto 8 cell stage (b) Either zygote or early embryo upto 8 cell stage(c) Embryo of 32 cell stage (d) Zygote only

Description : In vitro fertilisation is a technique that involves transfer of which one of the following into the fallopian tube? (a) Embryo only, upto 8 cell stage (b) Either zygote or early embryo upto 8 cell stage (c) Embryo of 32 cell stage (d) Zygote only

Last Answer : (b) Either zygote or early embryo upto 8 cell stage

(a) Draw a sectional view of the human heart and label on it – Aorta, Right ventricle and Pulmonary veins. (b) State the functions of the following components of transport system: (i) Blood (ii) Lymph -Biology

Description : (a) Draw a sectional view of the human heart and label on it – Aorta, Right ventricle and Pulmonary veins. (b) State the functions of the following components of transport system: (i) Blood (ii) Lymph -Biology

Last Answer : Answer.(a) (b) The functions of blood and lymph are as follows: (i) BloodOxygen is transported by the blood to the tissues of the body for the breakdown of digested food.Carbon dioxide is ... without which nothing will diffuse. (iii) A thin surface across which gases diffuse. (iv) Warm conditions.

Which one of the following statements regarding post-fertilisation development in flowering plants is incorrect? (a) Ovules develop into embryo sac. (b) Ovary develops into fruit. (c) Zygote develops into embryo. (d) Central cell develops into endosperm

Description : Which one of the following statements regarding post-fertilisation development in flowering plants is incorrect? (a) Ovules develop into embryo sac. (b) Ovary develops into fruit. (c) Zygote develops into embryo. (d) Central cell develops into endosperm

Last Answer : (a) Ovules develop into embryo sac.

Sex is determined in human beings (a) by ovum (b) at time of fertilisation (c) 40 days after fertilisation (d) seventh to eight week when genitals differentiate in fetus.

Description : Sex is determined in human beings (a) by ovum (b) at time of fertilisation (c) 40 days after fertilisation (d) seventh to eight week when genitals differentiate in fetus.

Last Answer : (b) at time of fertilisation

Which one of the following statements about human sperm is correct? (a) Acrosome has a conical pointed structure used for piercing and penetrating the egg, resulting in fertilisation. (b) The sperm lysins in the acrosome dissolve the egg envelope facilitating fertilisation. (c) Acrosome serves as a sensory structure leading the sperm towards the ovum. (d) Acrosome serves no particular function

Description : Which one of the following statements about human sperm is correct? (a) Acrosome has a conical pointed structure used for piercing and penetrating the egg, resulting in fertilisation. (b) The ... a sensory structure leading the sperm towards the ovum. (d) Acrosome serves no particular function

Last Answer : (b) The sperm lysins in the acrosome dissolve the egg envelope facilitating fertilisation.

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.

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

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.

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.

What is the work of copper-T? (a) To inhibit ovulation (b) To inhibit fertilisation (c) To inhibit implantation of blastocyst (d) To inhibit gametogenesis

Description : What is the work of copper-T? (a) To inhibit ovulation (b) To inhibit fertilisation (c) To inhibit implantation of blastocyst (d) To inhibit gametogenesis

Last Answer : c) To inhibit implantation of blastocyst

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.

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

How is the entry of only one sperm ensured into an ovum during fertilisation in humans? -Biology

Description : How is the entry of only one sperm ensured into an ovum during fertilisation in humans? -Biology

Last Answer : During fertilisation, a sperm comes in contact with the zona pellucida layer of the ovum and induces changes (depolarisation) in the membrane that blocks the entry of additional sperms. This ensures that only one sperm can fertilise an ovum

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 womb of other cows (b) in the eight cell stage the individual cells are separated under electrical field for further development in culture media (c) from this upto eight identical twins can be produced (d) the egg is divided into 4 pairs of cells which are implanted into the womb of other cows.

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

Which extra-embryonic membrane in human prvents desiccation of the embryo inside the uterus?

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.

Which extra-embryonic membrane in human prvents desiccation of the embryo inside the uterus?

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 sac B. Amnion C. Chorion D. Allantois

During Implantation, the blastocyst beco,es embedded in which layer of the uterus?

Description : During Implantation, the blastocyst beco,es embedded in which layer of the uterus?

Last Answer : During Implantation, the blastocyst beco,es embedded in which layer of the uterus? A. Trophoblast B. Endometrium C. Myometrium D. Perimetrium

Cu ions released from copper-releasing intra uterine devices (IUDs) (a) make uterus unsuitable for implantation (b) increase phagocytosis of sperms (c) suppress sperm motility (d) prevent ovulation.

Description : Cu ions released from copper-releasing intra uterine devices (IUDs) (a) make uterus unsuitable for implantation (b) increase phagocytosis of sperms (c) suppress sperm motility (d) prevent ovulation.

Last Answer : suppress sperm motility

The function of copper ions in copper releasing IUDs is (a) they inhibit gametogenesis (b) they make uterus unsuitable for implantation (c) they inhibit ovulation (d) they suppress sperm motility and fertilising capacity of sperms.

Description : The function of copper ions in copper releasing IUDs is (a) they inhibit gametogenesis (b) they make uterus unsuitable for implantation (c) they inhibit ovulation (d) they suppress sperm motility and fertilising capacity of sperms.

Last Answer : (d) they suppress sperm motility and fertilising capacity of sperms.

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.

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.

For the implantation of fertilize ova uterus secret which harmone?

Description : For the implantation of fertilize ova uterus secret which harmone?

Last Answer : Estrogen

The function of copper ions in copper releasing IUD's is : (1) They inhibit gametogenesis (2) They make uterus unsuitable for implantation (3) They inhibt ovulation (4) The suppress sperm motility and fertilising capacity of sperms

Description : The function of copper ions in copper releasing IUD's is : (1) They inhibit gametogenesis (2) They make uterus unsuitable for implantation (3) They inhibt ovulation (4) The suppress sperm motility and fertilising capacity of sperms

Last Answer : (4) The suppress sperm motility and fertilising capacity of sperms

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) High level of circulating FSH and LH in the uterus to stimulate implantation of the embryo (3) High level of circulating HCG to stimulate endometrial thickening (4) High levels of FSH and LH in uterus to stimulate endometrial thickening

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

The given figure depicts a diagrammatic sectional view of the human female reproductive system. Which set of three parts out of `I-Vi` have been corre

Description : The given figure depicts a diagrammatic sectional view of the human female reproductive system. Which set of three parts out of `I-Vi` have been corre

Last Answer : The given figure depicts a diagrammatic sectional view of the human female reproductive system. Which set ... (II) Myometrium , (III) Fallopian tube

Meiotic division of the secondary oocyte is completed (a) prior to ovulation (b) at the time of copulation (c) after zygote formation (d) at the time of fusion of a sperm with an ovum.Meiotic division of the secondary oocyte is completed (a) prior to ovulation (b) at the time of copulation (c) after zygote formation (d) at the time of fusion of a sperm with an ovum.

Description : Meiotic division of the secondary oocyte is completed (a) prior to ovulation (b) at the time of copulation (c) after zygote formation (d) at the time of fusion of a sperm with an ovum.

Last Answer : (d) at the time of fusion of a sperm with an ovum.

Identical twins are born when (a) Two sperms fertilise one ovum (b) Two sperms fertilise two ovums simultaneously (c) Open sperm fertilizes the ovum and zygote divides into two separate cells developing independently (d) One sperm fertilises two ovums

Description : Identical twins are born when (a) Two sperms fertilise one ovum (b) Two sperms fertilise two ovums simultaneously (c) Open sperm fertilizes the ovum and zygote divides into two separate cells developing independently (d) One sperm fertilises two ovums

Last Answer : Ans:(c)

A change in the amount of yolk and its distribution in the egg will affect (a) pattern of cleavage (b) number of blastomeres produced (c) fertilisation (d) formation of zygote.

Description : A change in the amount of yolk and its distribution in the egg will affect (a) pattern of cleavage (b) number of blastomeres produced (c) fertilisation (d) formation of zygote.

Last Answer : a) pattern of cleavage

From a to d which of the following statements are correct ? (a) Fertilisation can occur only if the ovum and sperm are transported simultaneously to t

Description : From a to d which of the following statements are correct ? (a) Fertilisation can occur only if the ovum and sperm are transported simultaneously to t

Last Answer : From a to d which of the following statements are correct ? (a) Fertilisation can occur only if the ovum and sperm ... b and c C. c and d D. b and d

What happens during fertilisation in humans after many sperms reach close to the ovum? (a) Secretions of acrosome helps one sperm enter cytoplasm of ovum through zona pellucida. (b) All sperms except the one nearest to the ovum lose their tails. (c) Cells of corona radiata trap all the sperms except one. (d) Only two sperms nearest the ovum penetrate zona pellucida.

Description : What happens during fertilisation in humans after many sperms reach close to the ovum? (a) Secretions of acrosome helps one sperm enter cytoplasm of ovum through zona pellucida. (b) All sperms except ... all the sperms except one. (d) Only two sperms nearest the ovum penetrate zona pellucida.

Last Answer : (a) Secretions of acrosome helps one sperm enter cytoplasm of ovum through zona pellucida.

Capacitation refers to changes in the (a) ovum after fertilisation (b) sperm after fertilisation (c) sperm before fertilisation (d) ovum before fertilisation.

Description : Capacitation refers to changes in the (a) ovum after fertilisation (b) sperm after fertilisation (c) sperm before fertilisation (d) ovum before fertilisation.

Last Answer : (c) sperm before fertilisation

Extrusion of second polar body from egg occurs (a) simultaneously with first cleavage (b) after entry of sperm but before fertilisation (c) after fertilisation (d) before entry of sperm into ovum.

Description : Extrusion of second polar body from egg occurs (a) simultaneously with first cleavage (b) after entry of sperm but before fertilisation (c) after fertilisation (d) before entry of sperm into ovum.

Last Answer : (b) after entry of sperm but before fertilisation

Endosperm is formed during the double fertilisation by (a) two polar nuclei and one male gamete (b) one polar nuclei and one male gamete (c) ovum and male gamete (d) two polar nuclei and two male gametes.

Description : Endosperm is formed during the double fertilisation by (a) two polar nuclei and one male gamete (b) one polar nuclei and one male gamete (c) ovum and male gamete (d) two polar nuclei and two male gametes.

Last Answer : (a) two polar nuclei and one male gamete