• Reproduction is a biological process in which an organism gives rise to young ones. It is a fundamental feature of all known life. Reproduction enables the continuity of the species and produces genetic variations in organisms. 
• Reproduction not only maintains populations of the young and adult persons but also that of older adults.
• Reproduction is a key process that determines the distribution of people of various ages in a population, called age structure.
• So the correct option is D.
  

Fertilised ovary is technically called fruit. But if ovary develops into fruits, without fertilisation, it is called parthenocarpic fruit. Such fruits are generally seedless. Some common examples found in nature are: Citrus, banana, etc., Parthenocarpy can be artificially induced too by application of certain plant hormones, especially, auxins and gibberellins.

• Reproduction is an essential process required for continuity of life and survival of species generation after generation. 
• An individual has a limited lifespan and lives for a defined time period but species survive and evolve for a much longer duration. Reproduction serves no other purpose and is not required for energy production or growth of an organism.

Reproduction can be defined as the biological process by which new individuals or offsprings are produced from their 'parents'. Offsprings are little similar to their parents.
Budding is a type of asexual reproduction by which offsprings arise from a single organism.

Reproduction is a process by which there is the production of a new organism by combining the genetic material of two different individuals. It occurs in eukaryotes. A process similar to sexual reproduction (conjugation, transduction, transformation) also takes place in prokaryote also but it is not a reproduction.

Reproduction is important because, with the help of reproduction, a new generation of species are produced. With the help of reproduction, genetic traits of that species are transferred from one generation to another.

A. Human show spontaneous ovulation that means ovum is released in every menstrual cycle irrespective of the fertilization event.

Reproduction is the biological process, through which a new organism produced from their parents. It is of two types - sexual reproduction, asexual reproduction. Asexual reproduction occurs through the involvement of the single parent. It occurs by many methods e.g .budding, fragmentation, spores. Asexually reproduce offspring is an identical copy of their parents. Sexual reproduction occurs through the involvement of two parents. It occurs through the male and female gametes. Sexually reproduce offspring are less similar to their parents. Reproduction is always observed in living organisms.

• Reproduction is the process by which living organisms produce new offspring similar to themselves.
• All living organisms do not have the capacity to reproduce. For example worker honeybees, mule or sterile human couples. Despite their inability to reproduce, they show other characteristics of living organisms.

• Water is an very important liquid present in the living world. Life has began in the water and the living organism cannot part from the water. They depend on water in major ways to continue their bodies major function.
• 70% of the animal body is made up of water. It helps in maintaining or maintains many functions of the body. Such as digestion and absorption of food which take place in the alimentary canal where the digested food is broken down with the help of water molecules into small absorbable component. Also after digestion some of the nutrients are absorbs along with water in the  digestive tract.
• As water itself talks long time to change its temperature compared to its surrounding it also helps in maintaining body temperature as the body is made up of 70% water and so the temperature of body is maintained. Where as the process of sweating and transpiration also release water to cool of the body when ever the temperature of body rises.
• Water is known to be an universal solvent as it can solve any polar solute such as salt, sugar, gases etc in the water, water molecule also form electrostatic bonds with ions who are partially soluble in pure water. Non polar solute are very poorly soluble in water.
• Also water is an important medium for reproduction. As the gametes that are required for the sexual reproduction cannot be produced with the water medium.
• Water works as the shock absorber for the brain and the spinal cord and protects them from the mechanical shock. As water is present in the fluid surrounding these organs.
  
• Therefore water is required for one function or the other in the body.
• Therefore the correct answer is option D 
  

Reproduction a process which is only possible by living organisms. So, reproduction exists as the defining property of living organisms.

Cleidoic eggs are those eggs, which have a protective shell, and are laid out of water. The shell is porous to air and may be flexible or calcareous (hard). The eggs contain all the food the embryo needs to develop into a hatchling. The significance of the cleidoic egg is that it enables reproduction out of and often away from water. The eggs of insects and birds, which is enclosed in a protective shell limiting the exchange of water, gases, etc. These type of eggs are found in reptiles, birds and monotremes. Therefore, non-cleidoic eggs will be found in fishes. Hence, option B is correct.

Most reptile eggs are leathery. It protects them when laid in holes, where they drop into contact with other eggs and it serves to make them more resilient, when covering the eggs with sand, dirt and other debris to conceal them. Hence, option B is correct.

Cleidoic eggs are those eggs, which have a protective shell, and are laid out of water. The shell is porous to air, and may be flexible or calcareous (hard). The eggs contain all the food the embryo needs to develop into a hatchling. The significance of the cleidoic egg is that it enables reproduction out of, and often away from, water. The eggs of insects and birds, which is enclosed in a protective shell limiting the exchange of water, gases, etc. These type of eggs are found in reptiles, birds and insects. Hence, option A is correct.

Centrolecithal egg, an egg in which the yolk is concentrated near the center of the egg cell, as is the case in many of the insects. Hence, it is correct match.
Megalecithal eggs are those eggs in large amount of yolk is present. Reptiles and birds are examples of this and not eutherian mammals, where alecithal egg is found.
Microlecithal eggs are those eggs in which small amount of yolk is present. Sea urchin, marsupials and amphioxus are examples of this and not reptiles, where megalecithal eggs are found.
Alecithal eggs are those eggs in which small amount of yolk is found. Mammals including humans are example of this and not birds, where megalecithal eggs are found.
Hence, option A is correct, which is only correct match out of given options.

• Cleidoic eggs are those eggs, which have a protective shell, and are laid out of water. 
• The shell is porous to air, and maybe flexible or calcareous (hard). The eggs contain all the food the embryo needs to develop into a hatchling. 
• The significance of the cleidoic egg is that it enables reproduction out of, and often away from, water. 
• The eggs of insects and birds, which is enclosed in a protective shell limiting the exchange of water, gases, etc. These types of eggs are found in reptiles, birds, and insects. Hence, option B is correct.

Enormous amount of yolk is present in megalecithal eggs and here yolk is several times greater than cytoplasm and yolk is concentrated in the interior of the egg and the cytoplasm is distributed as a thin layer on the outside of the yolk in centrolecithal eggs. These type of eggs is a characteristic of insects. Hence, option C is correct.

Mesolecithal egg are those eggs that has a yolk of intermediate size and strongly concentrated in one hemisphere. The young hatch at a later stage of development. It is a characteristic of lung fishes and amphibians likes frog. Hence, option B is correct.

Enormous amount of yolk is present in megalecithal eggs and here yolk is several times greater than cytoplasm. These eggs may be small or big. These types of eggs are characteristics of of teleost fishes, reptiles, birds. Yolk of egg is used for two purposes; supply of energy and synthesis of the products required for elaboration of the embryonic body.

• Reproduction is the biological process in which new individual organisms 'offsprings' are produced from their parents (existing organisms).

• Development is the act or process of growing or causing something to grow or become larger or more advanced.

Mutations are the permanent changes in the nucleotide sequence of the genome of an individual. These can occur during replication of DNA or its exposure with radiations or carcinogens, etc.

The life span of dog is 16 - 18 years. Life expectancy in dogs can be affected by many factors including genetic disease, diet, and exercise, similar to humans. Life expectancy usually varies within a range. For example, a Beagle (average life expectancy 13.3 years) usually lives to around 12–15 years, and a Scottish Terrier (average life expectancy 12 years) usually lives to around 10–16 years.

A woman is fertile, on average, between the ages of $12$ to $15$. During these fertile years, a recurring process - known as the menstrual cycle - takes place each month. This involves the lining of the uterus preparing for pregnancy. If pregnancy does not occur, the lining breaks down and the woman has a period. This is also known as menstruation. During this period which is generally from day $1$ to the day $7$ of the cycle, the intercourse does not result in pregnancy.

In women, both sex chromosomes are the same and are therefore called as XX. In males, they are different and called as XY. When sperm and eggs (ova) are made during meiosis they separate to form different gametes. As women have XX, their eggs always carry the X chromosomes. As males have XY, approximately half their sperm carry the X chromosome while the remainder carries the Y chromosome.

Reproduction is the process of continuation of a species. It is a mode of production of new organisms, called offsprings, from their parents. Each organism exists due to reproduction. With every new offspring, genetic variations are passed from the parents, that help the offspring survive better in the environment. Such variations and adaptations contribute to a species sustaining life for a longer duration.

• Character that are transmitted from parent to offspring during reproduction are similar to parent but they may vary due to mutation, crossing over and genetic recombination.

Offspring formed as a result of sexual reproduction exhibit more variations because genetic material comes from two parents of the same species.

• Reproduction is the method of making a copy of organisms or reproducing young ones. During reproduction, meiosis is the first stage by which gametes are prepared. 
• Each gamete contains a copy of male or female parents. When a zygote is formed by the fertilization of the gametes, the genetic copy of both the parents come into the offspring. Thus, it helps in the passing of genes.

Natural cytokinins are synthesized in regions where rapid cell division occurs, for example, root apices, developing shoot buds, young fruits etc. They promote nutrient mobilization which helps in the delay of leaf senescence.

So, the correct option is 'Cytokinin initiates senescence'

Sexual reproduction is the production of new living organisms by combining genetic information from two individuals of different types (sexes). In most higher organisms, one sex (male) produces a small motile gamete which travels to fuse with a larger stationary gamete produced by the other (female). Nearly all animals employ a diploid-dominant life-cycle strategy in which the only haploid cells produced by the organism are the gametes. Early in the development of the embryo, specialized diploid cells, called germ cells, are produced within the gonads (such as the testes and ovaries)

Reproduction  is the biological process by which new individual organisms – offspring – are produced from their parents. Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction. Reproduction in human beings is by sexual reproduction where both the male and female gametes fertilize to give rise to an embryo. The fertilization of human embryo occurs inside the body of the female 

• Reproduction is the biological process by which new individual organisms or 'offsprings' are produced from their 'parents'. Reproduction is a fundamental feature of all known life; each individual organism exists as a result of reproduction. 
• Though it is not essential, meaning, if someone does not reproduce, it will not end his life.

• Reproduction is the process that ensures continuity of species. All Individuals of any species die after their lifespan but some of them leave behind offsprings that will ensure continuity of species.
• Sterile members of any species, worker bees, mule etc. Complete their lifespan without reproduction. Hence, reproduction is not essential for any individual. 

The hymen is often torn during the first coitus. the presence or absence of the hymen is not a reliable indicator of virginity or sexual experience.

The mons pubis is the rounded eminence, made by fatty tissue beneath the skin, lying in front of the pubic symphysis. The antrum is the portion of an ovarian follicle filled with follicular fluid. The trophectoderm is a layer of cells on the outer edge of a blastocyst. These cells provide nutrients for the developing embryo, facilitate attachment to the uterine lining and become part of the placenta. The nebenkern is a mitochondrial formation in the sperm of some insects such as Drosophila.