BIOLOGY M.C.Q (1 Marks)

3. H. Spemann

Explanation:

The Spemann - Mangold organizer is the Spemann organizer, which describes the cluster of cells in the developing embryo of an amphibian, that induces development of the central nervous system.

The discovery of the Spemann - Mangold organizer introduced the concept of induction in embryonic development. 

4. LH.

Placenta also acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (HCG), human placental lactogen (HPL), estrogens, progestogens, etc.

1. Follicular cells around the oocyte.

3. Sertoli cells

Explanation:

Sustentacular cells are the cells that are associated with providing structural support.

A type of sustentacular cells is Sertoli cells which are found in the stratified epithelium of seminiferous tubules.

Sertoli cells are also known as supporting cells.

They are elongated and pyramidal which partially envelope the spermatogenic cell which nourish the spermatozoa.

4. 8^th month

Explanation:

During the 8th month, the baby's organs are fully developed like fingernails, brain except for lungs.

2. To provide nourishment to sperms

Explanation:

The prostate gland is a chestnut-shaped gland located between the bladder and penis in males. 

Its secretion provides nourishment and protection to the sperms. 

The muscles of the prostate gland also help in propelling the seminal fluid into the urethra during ejaculation. 

Its secretion forms about one - third of the volume of semen and contain various enzymes, zinc and citric acid. 

1. Testis

Explanation:

The inside of the testes is divided into small compartments called lobules.

Each lobule contains a section of seminiferous tubule lined with epithelial cells.

1. Seminal fluid

Explanation:

Seminal fluid, i.e., semen contain spermatozoa and is secreted by males.

Seminal fluid contains many components apart from spermatozoa like proteolytic enzymes and other enzymes, fructose, ascorbic acid, prostaglandins, etc., and some substances promote the survival of spermatozoa.

On the other hand, vaginal fluid, uterine lining and fallopian tube are components of female reproductive system.

3. Starts in fallopian tube.

4. Around urethra

Explanation:

Prostate gland is present around urethra.

The prostate gland is the accessory genital gland which occurs only in the male mammal.

It is unpaired. It is located below the urinary bladder. It secretes an alkaline fluid.

This fluid is rich in bicarbonate ion that neutralizes the acids in the female reproductive tract.

1. Spermatogenesis

Explanation:

In all mammals, the testes descend into the scrotum, which is outside the body cavity.

Here, the temperature is 1 - 6 degree celsius lower than inside of the body.

 The germ cells undergo mitosis and forms group of cells which is known as spermatogonia.

Spermatogonia is diploid and undergoes mitosis to form primary spermatocyte which further undergoes meiosis to form haploid secondary spermatocyte.

The secondary spermatocyte undergoes meiosis II to form haploid spermatids.

The spermatids get transformed into spermatozoa by the process of spermiogenesis turns into active sperms.

1. Corpus luteum.

1. Cuboidal.

1. Zona pellucida.

2. Occurs just prior to ovulation.

1. Unfertilized egg and the lining from the uterus leave the body.

Explanation:

When an egg is not fertilized by sperm in a woman's body the process of menstruation takes place where the upper soft layers of the uterus which are formed to hold the fertilized egg is shed outside the body along with the unfertilized egg if fertilization does not take place.

So, the correct answer is 'Unfertilized egg and the lining from the uterus leave the body'.

2. Non Primates.

2. Estrogen secretion further decreases.

1. Development of : Secretory phase and increased secretion of progesterone.

4. Seminiferous tubule

Explanation:

The male urethra provides a common pathway for the flow of urine and semen, the combined secretions of the male reproductive organs.

It is about 19 to 20 cm long and consists of three parts. The prostatic urethra originates at the urethral orifice of the bladder and passes through the prostate gland.

The membranous urethra is the shortest and narrowest part and extends from the prostate gland to the bulb of the penis, after passing through the perineal membrane.

The spongiose or penile urethra lies within the corpus spongiosum of the penis and terminates at the external urethral orifice in the glans penis. 

The penis has a root and a body.

The root lies in the perineum and the body surrounds the urethra.

It is formed by three cylindrical masses of erectile tissue and involuntary muscle.

The erectile tissue is supported by fibrous tissue and covered with skin and has a rich blood supply. T

he two lateral columns are called the corpora cavernosa and the column between them, containing the urethra, is the corpus spongiosum.

At its tip it is expanded into a triangular structure known as the glans penis.

Just above the glans the skin is folded upon itself and forms a movable double layer, the foreskin or prepuce.

The seminiferous tubules are a part of male testes. In each testis are 200 to 300 lobules and within each lobule are 1 to 4 convoluted loops composed of germinal epithelial cells, called seminiferous tubules.

2. Luteal

Explanation:

Menstrual cycle occurs in three major phases namely menstrual phase, proliferative phase and secretory phase. 

Proliferative phase is regulated by the hormones secreted by anterior pituitary gland whose secretion stimulates the ovarian follicle to secrete oestrogen.

During the second week, most of the developing follicles die and one follicle continues to grow and gets mature to form Graafian follicle.

This follicle undergoes ovulation on 14th day of the cycle.

Secretory phase is marked by the presence of corpus luteum (yellow body). This phase is also called luteal phase. 

In the presence of pregnancy this yellow body secretes human chorionic Gonadotropin (hCG) and in the absence of pregnancy, it regresses to form corpus albicans and menstruation starts (menstrual phase).

Since, ovulation occurs in Luteal phase, fertilisation can occur in Luteal phase.

1. Alveoli → mammary tubules → mammary duct → ampulla→lactiferous duct.

2. Mitochondria only.

1. Seminiferous tubules.

1. Spermiation.

2. One ovary only.

2. Prostate gland

Explanation:

The prostate gland lies in the pelvic cavity in front of the rectum and behind the symphysis pubis, surrounding the first part of the urethra.

The prostate gland secretes a milky fluid that makes up about 30% of semen with the milky appearance. 

It is slightly alkaline, which provides a protective local environment for sperm arriving in the acidic vagina.

It also contains a clotting enzyme, which thickens the semen in the vagina, increasing the likelihood of semen being retained in the vicinity of the cervix. 

Secretions of this gland, along with secretions of seminal vesicles, also make the seminal plasma rich in fructose, calcium and certain other enzymes too. 

1. FSH

Explanation:

Menopause refers to the stoppage of menstrual cycle in human females.

Follicle stimulating hormone (FSH) promotes development of ovarian follicles every month during menstrual cycle. 

FSH levels are elevated in women with menopause, ovariectomy, ovarian agenesis and Turner syndrome. 

4. Seminal vesicles, prostate and bulbourethral gland.

1. Tunica albuginea

Explanation:

Tunica albuginea is the fibrous envelope of the testes.

Tunica media lies between the tunica intima on the inside and the tunica externa on the outside.

Tunica vasculosa is the vascular layer of the testis.

Tunica vaginalis is a mesothelium-lined sac.

4. Both A and C

Explanation:

Estrogen hormone is used to inhibit the production of FSH and LH in females.

During menopause, the level of estrogen in the blood decreases, so estrogen can not inhibit the FSH and LH at the time of menopause.

Therefore, FSH and LH are produced after menopause in large quantities, which are excreted out in the urine.

4. Epididymis is involved in storage, nutrition and maturation of ova.

Explanation:

Ovaries, Uterus and Oviducts are parts of the female reproductive system.

Ovaries produce the female gamete and female hormones. 

The Uterus is the organ in which fertilized egg or zygote is implanted. 

The Oviducts are the ducts through which eggs pass through for fertilization.

The same ducts are used to transfer fertilized egg to the uterus for implantation. 

The epididymis is a thin tube that carries sperm from the testes to the ductus deferens in the male reproductive system and inside the Epididymis maturation and concentration of sperm occurs. 

1. Fructose and calcium

Explanation:

Seminal plasma in human males is rich in fructose and calcium because it provides nourishment and protection to spam and also provides a medium for transport.

3. Four, One.

4. Nurse cells

Explanation:

Sertoli cells occur in human testes.

Each lobule of testes contains one to three seminiferous tubules in which the sperms are produced.

Each seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and sertoli cells.

Sertoli cells are also called nurse cells because they provide nutrition to spermatozoa.

Spermatozoa are developing sperms.

Heads of spermatozoa are embedded in the sertoli cells.

3. Stage of development resembling other species.

Explanation:

In the embryonic developmental stage, an embryo develops within the amniotic sac, under the lining of the uterus.

This stage is characterized by the formation of most internal organs and external body structures.

It is also characterized by the stage of development resembling other species. 

3. Oogenesis

Explanation:

Oogonia develops into the primary oocytes. 

In meiosis I the primary oocyte forms a polar body and a secondary oocyte.

After meiosis I, the haploid secondary oocyte initiates meiosis II. 

When meiosis II is completed, an ootid and another polar body is created.

Polar bodies degenerate at the end of meiosis II, leaving only the ootid that develops into a mature ovum. 

3. Formative cells.

3. Fertilization – Zygote – cleavage – Morula – Blastula - Gastrula.

4. Progesterone level is high during the post ovulatory phase of menstrual cycle.

High levels of LH and FSH trigger the ovulatory surge. Sperms released from seminiferous tubules are non-motile. Oogonial cells cease activity when the girl child is still in the womb. Hence, option ‘d’ is the correct answer.

2. FSH and LH

Explanation:

LH and FSH are hormones secreted by the anterior pituitary.

The release of the oocyte from the ovary is called ovulation.

The LH bring about ovulation while FSH helps in the development of ovary.

1. Production of plasma of semen, protection and nourishment of sperm.

Explanation:

The function of prostate gland is to secrete a slightly alkaline fluid, milky or white in appearance, which protects the sperm from the acidic environment in female vaginal tract.

Also, provide nourishment and energy to the sperm.

Seminal vesicles secrete a significant proportion of the fluid that ultimately becomes the semen when mixed with sperm.

4. Spermatogonia, spermatocyte, spermatid, spermatozoa.

Explanation:

The correct sequence of sperm formation is:

Spermatogonia → Spermatocyte → Spermatid → Spermatozoa.

So, the correct answer is 'Option D- Spermatogonia, Spermatocyte, Spermatids, Spermatozoa'.

2. Graafian follicles

Explanation:

After ovulation, the graffian follicle matures into corpus luteum and acts as an endocrine gland.

It secretes luteinizing hormone, follicle stimulating hormone, oestrogen and progesterone. 

Vitelline membrane is an enveloped structure surrounding the outer surface of the plasma membrane in an ovum.

The supportive framework of an organ is called stroma.

The germinal epithelium is the epithelium layer of seminiferous tubules (testis) in males and ovarian surface (ovary) in females.

3. Gets implanted in endometrium by the trophoblast cells.

1. After entry of sperm but before completion of fertilization.

1. On either side of vagina in humans.

3. Isthmus.

3. Corpus luteum.

4. 9 million.