IGCSE Biology Paper-3: Specimen Questions with Answers 280 - 281 of 358

Passage

Reproduction is a characteristic of all living organisms.

Question 280 (4 of 4 Based on Passage)

Write in Short

Short Answer▾

The term sexual reproduction is in the box on the left.

The boxes on the right show some sentence endings.

Draw straight lines from sexual reproduction to the boxes on the right to make correct sentences.

Sexual Reproduction

Explanation

Sexual Reproduction

Sexual reproduction is the process in which male and female gamete fuse to form zygote through a process called fertilization and it is important for plants as it provides variation to the progeny that helps in the better survival and help it to gain its own uniqueness within the species and remove the unwanted genes.

The significance of sexual reproduction is:

  • parent can give birth to any number of children
  • two parents are involved
  • population increases

limitations of asexual reproduction:

  • after reproduction the parent organism disappears
  • one parent is involved

Passage

Fig. is a diagram of a fetus in the uterus.

Diagram of a Fetus in the Uterus

Question 281 (1 of 3 Based on Passage)

Write in Short

Short Answer▾

Table shows one of the names and the functions of some of the labelled parts shown in Fig.

Complete Table using the information in Fig.

One of the Names and the Functions of Some of the Labelled Parts
name of partletter in Fig.function
amniotic saccontains amniotic fluid
carries materials betweenmother and fetus
dilates during birth

Explanation

One of the Names and the Functions of Some of the Labelled Parts
name of partletter in Fig.function
amniotic sacBcontains amniotic fluid
placentaDcarries materials between mother and fetus
cervixCdilates during birth
  • After implantation, finger-like projections appear on the trophoblast called chorionic villi which are surrounded by the uterine tissue and maternal blood.
  • The chorionic villi and uterine tissue become interdigitated with each other and jointly form a structural and functional unit between developing embryo (fetus) and maternal body called placenta.
  • The placenta facilitates the supply of oxygen and nutrients to the embryo and removal of carbon dioxide and excretory/waste materials produced by the embryo.
  • The placenta is connected to the embryo through an umbilical cord which helps in the transport of substances to and from the embryo.
  • Placenta also acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (hCG) , human placental lactogen (hPL) , estrogens, progestogens, etc.
  • In the later phase of pregnancy, a hormone called relaxin is also secreted by the ovary.
  • Let us remember that hCG, hPL and relaxin are produced in women only during pregnancy.
  • In addition, during pregnancy the levels of other hormones like estrogens, progestogens, cortisol, prolactin, thyroxine, etc. , are increased. (essential for supporting the fetal growth, metabolic changes in the mother and maintenance of pregnancy) .
Diagram of a Foetus