Question

Which of the following taxa shows zooidogamous oogamy?
(I) Spirogyra
(II) Funasia
(III) Pteris
(IV) Cycas
The correct answer is
A. I,II,III
B. I,III,IV
C. I,II,IV
D. II,III,IV

Answer 1

We know that zooidogamous oogamy is a form of sexual reproduction where one biflagellate antherozoid fuses with the egg produced by the archegonium to form up a zygote. The zygote thus formed is usually sporophyte as well as multicellular. Thus, we know that it is a characteristic of bryophytes, pteridophytes as well as gymnosperms.

Complete answer:
We all know that sexual reproduction in plants takes place in different ways among different groups of species. The male gamete fuses with the female gamete to give out the product, ie. zygote. Zooidogamy and siphonogamy are the two ways in which male gametes travel towards the female gamete.
Zooidogamy is a type of fertilization which is seen in certain plants in which male gametes swim in the water to reach the female gamete. Thus, male gametes are motile and flagellated, which helps them to swim in water. For example, bryophytes, pteridophytes and some gymnosperms exhibit zooidogamy during sexual reproduction. Therefore, they are termed as zooidogamy plants. It is similar to reproduction that takes place in animals as in where there should be atleast on motile gamete to be formed. In them we know that male gamete is motile that swims towards the female gamete to exhibit fertilization to take place.
In spirogyra, sexual reproduction takes place by fusion of male gamete with the female gamete that are non - flagellated as well as non - motile but are similar in size. This condition is termed as isogamy.
In funaria, a liberated antherozoid has to swim towards the female archegonium in the presence of water. The male gamete is thus motile and flagellated because of which it is able to swim.
In pteris, the vegetative reproduction takes place by eventual death and decaying of the older sections of the rhizome. They thus belong to the class pteridophytes.
In cycas, they are oogamous where the male gamete is significantly larger than the male. Male and female sex organs are born on separate plant. The male gamete being motile reaches up the female gamete in order to take in for fertilization.

So, the correct option is D, II,III,IV.

Note: Zooidogamy is a type of oogamy which relates to evolution as it provides a pathway for a wind- borne abiotic pollination and similar mechanism to fluid- based mechanism that is used in most of the animals. It can only occur when the gamete shows motility for fertilisation. The zygote is a sporophyte with a multicellular body and remains attached to the photosynthetic gametophyte for its nutrition