The probability of fruit set in a self-pollinated bisexual flower of a plant is far greater than a dioecious plant. Explain.
The probability of fruit set in a self-pollinated bisexual flower of a plant is far greater than a dioecious plant.
In self-pollinated bisexual plants transfer of pollen to stigma of flowers is easier than the dioecious plants. It is so because the anther and stigma lie close to each other and pollination is not effected even in the absence of pollinator. But in dioecious plants pollinator is necessary to bring about effective pollination as the anther and stigma lie away from each other.
Is the presence of large number of chromosomes in an organism a hindrance to sexual reproduction? Justify your answer by giving suitable reasons.
No, presence of large number of chromosomes in an organism is not a hindrance to sexual reproduction. Ophioglossum (a fern) has chromosome number 1260, still it can reproduce sexually.
In higher organisms, the chromosomes are present in a compartment called nucleus, within the cell. Whether the number is small or large, the chromosomes are duplicated and then segregated inside this compartment, during cell division. The basis of sexual reproduction is generation of haploid gametes.
Is there a relationship between the size of an organism and its life span? Give two examples in support of your answer.
There is no relationship between the size and life span of an organism. e.g.,
(i) The mango tree has a shorter life span as compared to a peepal tree though both are of the same size.
(ii) The size of crow and parrot is almost same but the life span is 15 years and 150 years respectively.
In the figure given below the plant bears two different types of flowers marked ' $A$ ' and ' $B$ '. Identify the types of flowers and state the type of pollination that will occur in them.
$$ \text { In the figure given below the plant bears folllowing two types of flowers } $$
A-Chasmogamous flower (the flowers remain open, exposing anthers and stigmas).
B-Cleistogamous flowers (the flowers remain closed, so that anthers and stigmas are never exposed) following are the types of pollination that will occur in these flowers.
(i) Autogamy (within same flower)
(ii) Geitonogamy (different flowers of same plant)
(iii) Xenogamy (different plants)
It is a case of cleistogamy (a type of autogamy) in which some plants, like, Commelina bengalensis possess both chasmogamous and cleistogamous flowers.
In chasmogamous flowers, the flowers may undergo self-pollination or cross-pollination, while in cleistogamous flowers, the flowers undergo only self-pollination.
Give reasons as to why cell division cannot be a type of reproduction in multicellular organisms.
In unicellular animals, cell division is the means of reproduction to increase their number while, in case of multicellular organisms, they have well developed reproductive organs which help in reproduction.
Their whole body does not participate in reproduction like unicellular organisms.