The animals that reproduce asexually include planarians, hydra, amoeba, a few annelids, etc.

Formation of megaspores from megaspore mother cell called megasporogenesis. It occurs inside the nucellus of ovule of angiosperm. The process begins very early then nucellus is not completely surrounded by the integuments.

A diploid cell in the ovule, called a megasporocyte or a megaspore mother cell, undergoes meiosis and gives rise to four haploid megaspores.

he process of formation of megaspores from the megaspore mother cell.

• It is also called macrospores.
• The megaspore mother cell is diploid.

The menstrual cycle is a series of cyclic physiologic changes that take place inside the female reproductive tract in primates. The whole cycle takes around 28 days to complete. The end of the cycle is accompanied by the breakdown of uterine endothelium, which gets released in the form of blood and mucous through the ******. This is known as menses. The follicle stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone are the various hormones that regulate the menstrual cycle. The level of FSH and LH secreted from the anterior pituitary gland increases during the follicular phase. FSH secreted under the influence of RH (releasing hormone) from the hypothalamus stimulates the conversion of a primary follicle into a graafian follicle. The level of LH increases gradually leading to the growth of follicle and secretion of estrogen. Estrogen inhibits the secretion of FSH and stimulates the secretion of luteinizing hormone. It also causes the thickening of the uterine endometrium. The increased level of LH causes the rupturing of the graafian follicle and release the ovum into the fallopian tube. The ruptured graafian follicle changes to corpus luteum and starts secreting progesterone hormone during the luteal phase. Progesterone hormone helps in the maintenance and preparation of endometrium for the implantation of the embryo. High levels of progesterone hormone in the blood decrease the secretion of LH and FSH, therefore inhibiting further ovulation.

Unicellular organisms are considered immortal mainly because,in them the parent body as a whole constitutes the reproductive unit and after reproduction continues to live as daughter cells .

Griffith’s Experiment

Griffith experimented with Streptococcus pneumoniae bacteria. This bacteria causes Pneumonia.Two strains of this bacteria were used R-strain & S-strain.

• S strain
  • Smooth mucous polysaccharide coat
  • Resistant to immune system
  • Virulent
• R strain
  • Lacks the coat
  • Destroyed by immune system of the host
  • Non-virulent

The experiment was performed in multiple steps.

1. S-strain (virulent) was injected into mouse. It was found that the mouse died of pneumonia
2. R-strain (non-virulent) was injected into mouse. It was found that the mouse remained alive .
3. Heat killed S-strain (S-strain bacteria were killed by heating) was injected into mouse. It was found that the mouse remained alive .
4. Heat killed S-strain & live R-strain were injected into mouse. It was found that the mouse died of pneumonia

Mutations are changes in the genetic sequence, and they are a main cause of diversity among organisms. These changes occur at many different levels, and they can have widely differing consequences. In biological systems that are capable of reproduction, we must first focus on whether they are heritable; specifically, some mutations affect only the individual that carries them, while others affect all of the carrier organism's offspring, and further descendants. For mutations to affect an organism's descendants, they must: 1) occur in cells that produce the next generation, and 2) affect the hereditary material. Ultimately, the interplay between inherited mutations and environmental pressures generates diversity among species.

Although various types of molecular changes exist, the word "mutation" typically refers to a change that affects the nucleic acids. In cellular organisms, these nucleic acids are the building blocks of DNA, and in viruses they are the building blocks of either DNA or RNA. One way to think of DNA and RNA is that they are substances that carry the long-term memory of the information required for an organism's reproduction. This article focuses on mutations in DNA, although we should keep in mind that RNA is subject to essentially the same mutation forces. If mutations occur in non-germline cells, then these changes can be categorized as somatic mutations. The word somatic comes from the Greek word soma which means "body", and somatic mutations only affect the present organism's body. From an evolutionary perspective, somatic mutations are uninteresting, unless they occur systematically and change some fundamental property of an individual--such as the capacity for survival. For example, cancer is a potent somatic mutation that will affect a single organism's survival. As a different focus, evolutionary theory is mostly interested in DNA changes in the cells that produce the next generation.

The environment can also cause DNA mutations. Sunlight, cigarette smoke, and radiation are all known to cause changes to our DNA. These are also random and can happen anywhere in the DNA sequence. Sometimes these mutations don't change a gene at all and the protein stays the same. With base substitution mutations, only a single nucleotide within a gene sequence is changed, so only one codon is affected.

In binary fission, the parent cell divides itself into two equal and identical daughter cells. It is the most common form of reproduction in prokaryotes such as bacteria.
Binary Fission in amoeba: Most single-celled organisms use the method of binary fission for cell division and reproduction. These include paramoecium, bacterium, and finally amoeba. In this paragraph, we will be focusing on amoeba’s cell division which is also its method of reproduction. In binary fission, the amoeba consists of one parent which forms the 2 daughter cells. First, the amoeba cell undergoes nuclear division and replicates into two nuclei. The two nuclei divide and move to opposite directions in the parent cell. The cell then produces proteins and nutrients in preparation for binary fission. In the stage of binary fission, the cell divides and forms 2 daughter cells. This process generally occurs when environmental conditions are most favorable. That is when there is enough food, water, and a favorable temperature.

Plant hybridization is the process of crossbreeding between genetically dissimilar parents to produce a hybrid. It frequently results in polyploid offspring. Hybridization is generally defined as the interbreeding of individuals from two populations or groups of populations that are distinguishable on the basis of one or more heritable characters. By extension, a hybrid is an individual resulting from such interbreeding. 

Hormonal regulation of the male reproductive system: GnRH stimulates the production of FSH and LH, which act on the testes to begin spermatogenesis and to develop secondary *** characteristics in the male. The Sertoli cells produce the hormone inhibin, which is released into the blood when the sperm count is too high.

Colourblindness is an X-linked recessive trait caused due to the defective allele on the X chromosome.

In this problem,

Since the father is colourblind, his genotype would be XcY.

Although the woman has colourblind father, her vision is normal. This implies that she is a carrier of the trait. Therefore, her genotype would be.

This carrier woman marries a man with a normal vision.

From the above Punnett square, we can deduce that 50% of the daughter are carriers while 50% are normal. 50% of the sons are colourblind while 50% are normal. 

Cleavage may be total (holoblastic) or partial (meroblastic). In eggs with no yolk or only a moderate amount of yolk, cytokinesis completely divides the cell and cleavage is holoblastic. Here, cleavage furrows are formed all the way through the zygote. This form of cleavage occurs in mammals such as humans. In embryology, cleavage is the division of cells in the early embryo. The zygotes of many species undergo rapid cell cycles with no significant overall growth, producing a cluster of cells the same size as the original zygote.

Natural Birth Control

Natural birth control methods include total and continuous abstinence and the rhythm method. The rhythm method involves having no intercourse or protected intercourse during the time when the woman is fertile. A woman is fertile for 9 days every month during which she is most likely to conceive. The fertile period starts 5 days before ovulation and continues for 3 days after ovulation.

Cell division is the driving process of reproduction at the cellular level. Most eukaryotic cells divide in a manner where the ploidy or the number of chromosomes remains the same, except in the case of germ cells where the number of chromosomes is halved.

Pollen or nectar robbers are those animals, insects, birds that removes the nectar from a flowering plant without causing pollination.