Q.1. Name the stage in the life-cycle during meiosis in the haploid organisms that undergo sexual reproduction. Give reasons as well.
Answer- Meiosis takes place in the diploid stage. This is because the zygote is the only diploid cell in the life cycle of haploid organisms.
Q.2. In higher plants and higher animals, the number of taxa exhibiting asexual reproduction is drastically reduced as compared to the lower groups of plants and animals. Explain.
Answer- The higher plants and animals have a complex structure as compared to the lower plants and animals. They have well developed sexual reproductive organs. They are structured to reproduce sexually because of the following reasons:
- To ensure genetic recombination which results in variation and gives rise to evolution.
- Healthy progeny are produced.
- Genetically different off springs are produced.
Q.3. Name the haploid and diploid individuals in the family of honey bees and analyze the reasons behind their formation.
Answer- The sterile worker females are diploid. The fertile female queen bee is diploid. The male drones are haploid. The haploid and diploid individuals are formed both by unfertilized and fertilized eggs, respectively. The fertilized eggs from the female queen bee and the worker bee. The male drones are formed as a result of parthenogenesis, i.e., by unfertilized eggs.
Q.4. Which type of reproduction is a reduction division associated with? Give reasons in support of your answer.
Answer- Reduction division is referred to as meiosis and is associated with sexual reproduction. Reasons:
- The gametes that fuse should be haploid.
- The germ cells are diploid. Meiosis can only reduce the number to half.
Q.5. Is vegetative propagation considered a type of asexual reproduction? Give reasons.
Answer- Yes, vegetative propagation is a type of asexual reproduction. This is because:
- The new individuals are produced by a single parent.
- There is no fusion of gametes.
- They are the exact clones of their parents without any genetic or morphological variations.
Q.6. Why is fertilization not a compulsory event for the production of fruits in certain plants?
Answer- There are a few fruits such as grapes, pomegranate, etc. developed from the unfertilized ovaries. These are known as parthenocarpic fruits. The flowers of such plants are sprayed with a growth hormone that facilitates fruit production even without fertilization. But the ovules do not change into seeds.
Q.7. What will be the consequences if cell division is not followed by cell differentiation in a developing embryo?
Answer- Cell division increases the number of cells whereas cell differentiation helps the cell mass to form specialized tissues and organs. If cell division is not followed by cell differentiation, there will be no embryo development and it will remain only as a mass of the cell.
Q.8. What are the changes that take place in an angiosperm after pollination and fertilization have occurred?
Answer- Following are the changes that occur in an angiosperm after pollination and fertilization:
- The sepals, petals and stamens fall off.
- The zygote is converted into an embryo.
- The embryo is present in the ovule. Ovule forms the seed.
- Ovary wall develops into pericarp.
- Ovary forms the fruit.
Q.9.What is Embryogenesis?
Answer- Embryogenesis is the biological process by which the embryo is formed and developed into a fetus. Embryogenesis begins with the fertilization of the ovum by sperm.
Q.10.What is Fragmentation?
Answer- Fragmentation is an asexual mode of reproduction. In this, the parent organism splits into several parts and each part grows into a new individual. For eg., Planaria are a group of free-living flatworms reproduce their young ones through Fragmentation
Q.11.What is vegetative propagation?
Answer- Vegetative propagation is an asexual mode of reproduction occurring in plants. This includes both natural and Artificial method of vegetative propagation
Q.12.What is Sexual Reproduction?
Answer- Sexual reproduction is a natural way of reproducing young ones which are identical to their parents. In this type of reproduction, there is an involvement of both the parents. Sexual reproduction is observed only in multicellular organisms like animals, plants, mammals, humans, birds, etc.
Q.13.What is Gametogenesis?
Answer- Gametogenesis is the biological process by which diploid or haploid cells undergo cell division and differentiation to form produce mature haploid gametes In humans, during the process of gametogenesis the two different types of gametes are present.
- Male gametes – are called sperm.
- Female gametes- are called the ovum.
Q.14.What is a bisexual flower?
Answer- A flower is a reproductive part of a plant. Based on the reproductive organs present in a flower, it is classified into two – Bisexual and Unisexual flower.
The flower which includes both male (androecium) and female (gynoecium) reproductive organs is called the bisexual flower. A bisexual flower is also referred to as a perfect flower. Lily, rose, and Hibiscus are a few examples of the bisexual flower.
Q.15.What is Asexual Reproduction?
Answer- .Asexual reproduction is another mode of reproducing their offsprings. In this type of reproduction, there is an involvement of the only one parent. Asexual reproduction is observed in both multicellular and unicellular organisms.
Q.16.What are the different types of asexual reproduction
Answer- The different types of asexual reproduction are as follows
- Binary Fission
- Budding
- Fragmentation
- Vegetative Propagation
- Sporogenesis
Q.17.What is the complete process of sexual reproduction?
Answer- Sexual reproduction includes the following set of events:
- Pre-fertilization.
- Fertilization.
- Post-fertilization.
Q.18.Define Pollination?
Answer-.Pollination is a natural process of transferring pollen grains from an anther – the male part of a flower to the stigma – the female part of a flower. There are 2 types of pollination –
- Self Pollination
- Cross-Pollination
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