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

1 Answer

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 uterine tissue and maternal blood which become interdigitated with each other to form placenta. Events leading to formation of placenta. The chorionic villi and uterine tissue, after implantation become interdigitated with each other and form placenta, a structural and functional unit between embryo and maternal body. Functions of Placenta  (i) It facilitates the supply of oxygen and nutrients to the foetus and removal of C02 and excretion products. (ii) It acts as an endocrine gland and secretes hormones like hPL, hCG, oestrogen and progesterone.

Related questions

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.

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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.

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 : (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

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Last Answer : (d) gets implanted in endometrium by the trophoblast cells.

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Last Answer : (i)Development of placenta in human female After implantation of blastocyst, the finger-like projections called chorionic villi, appear on the trophoblast and is surrounded by uterine tissue and ... Chorionic Gonadotropin) (b) hPL (human Placental Lactogen) (c) Oestrogens (d) Progesteronem

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Last Answer : (c) High level of hCG stimulates the synthesis of estrogen and progesterone.

Description : Which of the following correctly explains the phenomenon of "Test Tube Bally"? (1) When every process of embryo formation is in the test tube. (2) When the embryo develops in a test tube ... is external and development is internal. (4) When the fertilisation is internal and development is external.

Last Answer : (3) When the fertilisation is external and development is internal. Explanation: Test tube baby is born from in vitro fertilization. In vitro fertilization (IVF) is a process by which an egg ... ) is then transferred to the patient's uterus with the intention of establishing a successful pregnancy.

Description : Which of the following correctly explains the phenomenon of Test Tube Baby ? (1) When every process of embryo formation is in the test tube. (2) When the embryo develops in a test ... is external and development is internal. (4) When the fertilisation is internal and development is external.

Last Answer : When the fertilisation is external and development is internal.

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

Last Answer : (d) fertilisation.

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,

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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

Description : Which of the following statements is correct with reference to a test tube baby? (a) Fertilisation of the egg is effected outside the body; the fertilised egg is then placed in the womb of the mother ... . (d) Fertilisation of the egg and growth of the embryo are affected in a large test tube.

Last Answer : (a) Fertilisation of the egg is effected outside the body; the fertilised egg is then placed in the womb of the mother where the gestation is completed.

Description : In some plants, the female gamete develops into embryo without fertilisation. This phenomenon is known as (a) parthenogenesis (b) autogamy (c) parthenocarpy (d) syngamy.

Last Answer : (a) parthenogenesis

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Last Answer : ANSWER: C -- ENDOMETRIUM AND EMBRYO 

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Last Answer : c) To inhibit implantation of blastocyst

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Last Answer : (b) Somatic embryos can develop from microspores.

Description : Adventive embryony in Citrus is due to (a) nucellus (b) integuments (c) zygotic embryo (d) fertilized egg.

Last Answer : nucellus

Description : Statement S. After implantation, the uterine endometrium undergoes changes to become decidus Reason R. the placenta in described as deciduous type Cor

Last Answer : Statement S. After implantation, the uterine endometrium undergoes changes to become decidus Reason R. the ... and R is a correct explanation to S.

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.

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Last Answer : (a) Two X chromosomes

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Last Answer : (d) implantation of embryo at site other than uterus.

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Last Answer : (1) High level of circulating HCG to stimulate estrogen and progesterone synthesis

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Last Answer : b)embryo

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

Description : (i) How is placenta formed in human female? (ii) Name any two hormones which are secreted by it and are also present in a non-pregnant woman. [ -Biology

Last Answer : i)After implantation of blastocyst, the finger-like projections called chorionic villi, appear on the trophoblast and is surrounded by uterine tissue and maternal blood which become interdigitated with each ... by placenta that are also present in a non-pregnant women are oestrogen and progesterone.

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Last Answer : Ans:(a)

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.

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Last Answer : (b) fertilisation in vitro and then transplantation in uterus

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

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Last Answer : (c) morula

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

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Last Answer : (d) development of embryo from egg without fertilisation.

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 : fertilisation in vitro and then transplantation in the uterus.

Description : In which trimester does the following occur A sac called a placenta forms around the embryo and is connected to the embryo with an umbilical cord.?

Last Answer : What is the answer ?

Description : The structure which helps in the nutrition of the Embryo is – (1) Yolk sac (2) Amniotic membrane (3) Crypts (4) Placenta

Last Answer : (1) Yolk sac Explanation: The yolk sac is a membranous sac attached to an embryo, providing early nourishment. It functions as the developmental circulatory system of the human embryo, ... It carries out transfer of nutrients in weeks 2 and 3 when the uteroplacental circulation is established

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 : Which one of the following is not the function of placenta? (a) Facilitates removal of carbon dioxide and waste material from embryo (b) Secretes oxytocin during parturition (c) Facilitates supply of oxygen and nutrients to embryo (d) Secretes estrogen

Last Answer : (b) Secretes oxytocin during parturition

Description : What structure attaches the embryo to the placenta?  

Last Answer : ANSWER: UMBILICAL CORD

Description : The structure which helps in the nutrition of the Embryo is (1) Yolk sac (2) Amniotic membrane (3) Crypts (4) Placenta

Last Answer : Yolk sac 

Description : Excretory products of mammalian embryo are eliminated out by (1) Placenta (2) Amniotic fluid (3) Allantois (4) Ureter

Last Answer : Placenta

Description : Match column I with column II and select the correct option using the given codes. Column I Column II A. Mons pubis (i) Embryo formation B. Antrum (ii) Sperm C. Trophectoderm (iii)Female external genitalia D. Nebenkern (iv) Graafian ... (i), C-(iv), D-(ii) (d) A-(i), B-(iv), C-(iii), D-(ii

Last Answer : (b) A-(iii), B-(iv), C-(i), D-(ii)

Description : Which is the most common type of embryo sac in angiosperms ? (a) Tetrasporic with one mitotic stage of divisions (b) Monosporic with three sequential mitotic divisions (c) Monosporic with two sequential mitotic divisions (d) Bisporic with two sequential mitotic divisions

Last Answer : (b) Monosporic with three sequential mitotic divisions

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

Description : Which of the following statement about reproductions in human is correct. a) fertilisation takes place externally b) fertilisation takes place in the testes c) during fertilisation egg moves towards sperm d) fertilisation takes place in human female

Last Answer : d) fertilisation takes place in human female

Description : .The fetal ejection reflex in humans triggers the release of (a) oxytocin from fetal pituitary (b) human chorionic gonadotropin (hCG) from placenta (c) human placental lactogen (hPL) from placenta (d) oxytocin from maternal pituitary.

Last Answer : (d) oxytocin from maternal pituitary.

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Last Answer : (b) fully developed fetus and placenta

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Last Answer : (b) apomixis

Description : Explain the post-fertilisation changes in a flower. -Biology

Last Answer : answer: