Tag: zoology

Gametes are the cells that merge with each other to create a unique organism during sexual reproduction. Gametes are the reproductive cells used to make a new organism called a zygote during sexual reproduction. There are distinct gametes in men and women. The sperm is called the male gamete. It's much lower and very mobile than the female gamete. It has a lengthy tail, flagellum, which makes it possible to move towards the female gamete. The egg or ova is called the female gamete. It's much bigger than the sperm and it's not moving

Unisexual animals have a reproductive structure that is either functionally male or functionally female. In angiosperms, this condition is also called diclinous, imperfect or incomplete. In animals, mostly the sexes are separate i.e. they are unisexual (male & female). For example, dogs, humans, tiger etc.

Monkey and Cat are mammals. They reproduce sexually. Higher animals do not reproduce asexually. Lower animals like Coelenterates reproduce asexually. Thus, the correct answer is option D.

Sexual reproduction in higher organisms is characterized by the formation of haploid gametes and their fertilization. The haploid gametes are produced by meiosis which has a half number of chromosomes as compared to the parent cell. It is also known as the reductional division. The haploid gametes obtained from both the parent fuse to form a diploid zygote. Mitosis is an equational division so it will not lead to the reduction in the chromosome.

The given statement is true. The daughter cells produced by asexual reproduction are similar to their parent i.e., they are genetically identical to their parent. In contrast, sexual reproduction produces a similar but genetically different offspring. In the process of sexual reproduction, haploid gametes produced by the meiotic division fuses to form a diploid zygote. A child inherits half of the genetic material from each parent. So, it may be they look alike but they are not identical to their parents. Instead, the child has the combination of characteristics inherited from both parents. Therefore, we can say that in sexual mode of reproduction, greater diversities are generated.

Greek word sexus means union. It is used in biology in terms of fusion of gametes in plants and animals. The male gametes is known as sperm and the female is known as ovum. Sexual reproduction is the reproduction which is caused by the fusion of gametes. The male and female gametes fuses to form zygote. 

• Mast cells are found in mucous membranes and connective tissues and are important for wound healing and defense against pathogens via the inflammatory response.
• The mast cell granules are composed of serotonin, heparin, and histamine. They secrete serotonin, heparin, and histamine when they are activated in the presence of the toxic substance or a pathogen.
• Hence Mast cells secrete 'serotonin, heparin, and histamine'.
• So, the correct answer is 'All the above'.

• The cells of the immune system can be categorized as lymphocytes (T-cells, B-cells and NK cells), neutrophils, and monocytes/macrophages. These are all types of white blood cells.
• Neutrophils are phagocytic cells that are also classified as granulocytes because they contain granules in their cytoplasm. These granules are very toxic to bacteria and fungi and cause them to stop proliferating or die on contact.
  
• B lymphocytes provide humoral immunity and T lymphocytes provide cellular immunity.
• Macrophages are efficient phagocytic cells that can leave the circulatory system by moving across the walls of capillary vessels. The ability to roam outside of the circulatory system is important because it allows macrophages to hunt pathogens with less limits. Macrophages can also release cytokines in order to signal and recruit other cells to an area with pathogens.
• Hence Neutrophils, Lymphocytes, and Macrophages are involved in body defense.
• So, the correct answer is 'All the above'.

Passive immunity is the transfer of active humoral immunity of ready-made antibodies (exogenous). Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta, and it can also be induced artificially when high levels of antibodies specific to a pathogen or toxin are transferred to non-immune persons through blood products that contain antibodies.

Active immunity is the induction of immunity after exposure to an antigen. Antibodies are created by the recipient and may be stored permanently due to the activation of memory cells which recognizes the same antigen in future and destroy them. Active immunity can occur naturally when a microbe or other antigen is received by a person who has not yet come into contact with the microbe and has no pre-made antibodies for defence. The immune system will eventually create antibodies for the microbe, but this is a slow process.