KPK Board 12th Class Biology Ch 21 Development and Aging Short Questions Answers

the progressive change that lead an organism to become a dalte are called development growth it is the enlargement of tissue organism growth continue after the embryonic stage.

the progressive changes that occur before an organism it adults from are called embryonic development begging it begins with a series of meiotic division Zygote this divisions are called  cleavage. further division:  for further division of morula causes the formation of three germinal layers that take part in the formation of various body systems.

the early division of zygote are called cleavage.

first cleavage the first clay which occurs on 36 hours after fertilization it give rise to two identical cells called blastomeres II cleavage divided plastomers into 4 cells morula : further cleavage form a loose collection of cells that looks like berry and is cluster of 16 or more cells called morula .

compaction at 8 cell stage the embryo goes through some changes most of blastoma in this stage become polarised and develop tight junction with other blastomeres this result polar cells and outside and a polar cells inside the outer cells called trophoblast pump sodium inform outside that brings water into basal cells in a process called compaction .

it is a structure formed in the early development of mammals in humans its formation begin five days after fertilization The outer layer of cells of blastocyst are called the trophoblast that surrounds the inner cells mass and a fluid filled cavity called blastocoels.

in human and other mammals implantation is a very early stage at which the embryo adheres to the walls of uterus importance it is by this adhesion that the foetus receives oxygen and nutrients from the mother to be able to grow.

The formation of three layered embryo is called gastrulation gastrula after 3 weeks of fertilization salary arrangement and migration give rise to an Empire you that consists of three germ layers namely ectoderm mesoderm endoderm at the state temperature is called the gastrula formation gastrulation begins when a groove with raised age primate streak appear on the dorsal surface of embryonic disc ectoderm it is formed by the cells on the dorsal surface of embryo this layer is formed by the Migration of cells laterally between the upper and lower surface and it is formed by the first cells that enter the group and displays hypoblast cells.

the primary germ layers are very important because they serve as the Prime Minister of tissue from which all body organs will drive their importance is in tissue formation is following actiderm it forms the structure of nervous system and skin epidermis mesoderm it for muscles skeletal system and circulatory system and order it take part in the formation of living of digestive respiratory and urine genital system and associated glands.

organ functional body part made up of tissue and Genesis main formation the formation of organs and system during embryonic development is called organogenesis in this process the ectoderm endoderm and mesoderm develop into internal organs of the organism the internal organs initiate development in human within the 38 weeks in uterus process the germ layers in organism organogenesis different by 3 process fold spletes condensation.

new regulation it is the folding process in vertebrate embryo which include the transformation of neural plate into neural tube new regular the embryo at this stage is called new ruler start the process begins when the notochord induced the formation of CNS.

nucleus has important role in development importance of nucleus was expressed in unicellular algae acetabularia .

video gana two types the two types of algae used wereKarna acetabularia mediterranea having umbrella shaped cap acetabularia crenulata having irregular shaped cap the cap of both were removed and thrown away their stalk were removed but exchange.

Matka result it was found that the new caps regenerated according to the type of nucleus present at their bases conclusions the nucleus exert a strong influence on the development of cap through mRN A.

which is the important stage in embryonic development because it produces the number of cells needed for the further organisation of the embryo it shaped the egg material and balance out the nuclear and cytoplasmic material the process of development is initiated by cleavage.

a normal human pregnancy last about 9 months Age 3 month period of pregnancy is called  a normal human pregnancy last about nine months is three month period of pregnancy is called  trimester It is form week 12  implantation Placenta formation organogenesis face having human profile second trimester it is for months 4 6 changes fetal sex become Apparent foetus grow rapidly internal organs continue to mature fingers have developed fingerprintsThird trimester it is for months 7 and 9 10 days foetus begins to move rapidly foetus head  descend to the pelvic cavity of mother.

in which the embryo implant in any site other than the uterus most friendly the site is uterine tube sense uterine tube as well as other ectopic site are unable to establish a pleasant or accommodate growth the pregnancy at the sides is not completed the uterine tube rupture and less the condition is is diagnosed early or pregnancy spontaneously abort.

identical twins are triplets come from a single fertilized egg that separate into two or more embryos during first stage of development fraternal the come from multiple fertilized egg and have separate amniotic sac and placenta.

Placenta is an organ that connect the developing foetus to the uterine wall to allow nutrient uptake waste elimination and gas exchange umbilical cord the play Santa Claus attached to the embryo by a tube called umbilical cord importance place and help in exchange of material between mother and foetus ipravent harmful substances from reaching to the embryo it produces hormones for maintaining pregnancy.

it  is the the secretion of milk from mammary gland and the period of time that a mother lactates to feed her young in most species the process can occur with almost post pregnancy.

write some disadvantages of bottle feeding?

sum of digits advantages of bottle feeding are following it can create unhygienic condition for baby it can easily cause various kinds of infections it can cause in digestion it is not  efficiently utilised it has difficulty for some babies to utilise certain nutrients bottle feeding babies have also a risk of developing and allergy.

It is commonly known as German measles. It is a disease caused by rubella virus infection of Mother by rubles virus during pregnancy  can be serious if the mother is infected within the first 20 weeks of pregnancy  the child may be born with congenital rubella syndrome that can sometimes be fatal.

symptoms of the flu however the primary symptoms in appearance rash on the face which separate to the trunk and Limbs usually fades after 3 days.

It stand for neural tube defect these are serious birth defects they are caused by incomplete development of the brain and spinal cord are there protective membrane it occur when the foetus spine fails to close properly during the early stage of pregnancy prevention women who may be become pregnant  are advised to get 400 milligram of folic acid daily.

the lifespan of the ovarian Corpus luteum is extended for nearly three month after implantation but otherwise it deteriorates.

Corpus luteum is a yellow hormone secreting body in human females found in an ovary at the site of a follicle or sac.

When the egg is not fertilized it stops secreting progesterone and after approximately 14 days the uterine is expelled .

When implantation occurs the HCG signals the Corpus luteum to continue progesterone for maintaining the pregnancy.

what factors are believed to bring about uterine contraction at the termination of pregnancy/

uterine contractions are labour contraction are the periodic tightening and relaxing of the uterine muscles Oxytocin is responsible for uterine contraction.