Year: 2021

A phenomenon is termed parthenogenesis when                                                                                                 [CBSE PMT 1990]              (a)   Artificial fertilization occurs              (b)   Egg is fertilized by a sperm              (c)   Egg undergoes cleavage without fertilization              (d)   Sperm dies before fertilization Which of the drug …

          Reproduction and its type Which are exclusively viviparous                          [AFMC 1986]              (a)   Bony fishes                           (b)   Cartilagenous fishes              (c)   Sharks                                    (d)   Whales The asexual process replaced by the sexual method is known as          …

“Sertoli cells” in human testis are found in [CPMT 1980, 83, 94,99; DPMT 1986; AFMC 2002]              (a)   Seminiferous tubules              (b)   Leydig cells              (c)   Outside the seminiferous tubules              (d)   None of these In man the epididymis from …

Penetration of sperm is a chemical mechanism. In this acrosome of sperm undergoes acrosomal reaction and releases certain sperm lysins which dissolve the egg envelopes locally and make the path for the penetration of sperm. Sperm lysins are acidic proteins. …

(iii) Mucous membrane : It is the innermost layer. This layer is made up of ciliated columnar epithelium and the connective tissue. The oviduct shows 4 regions : (a) Infundibulum : It is the broad, funnel-shaped proximal part. Its margin …

  Reproduction and its type Reproduction : Reproduction is the ability of living organism to produce a new generation of living individuals similar to themselves. Basic features of reproduction : All organisms reproduce. Modes of reproduction vary in different organisms. …

Histones are synthesised during [CBSE PMT 1992]              (a)   Mitosis                                   (b)   S phase              (c)   G1 phase                                (d)   G2 phase Multiplicative growth is not found in              (a)   Higher vertebrate               (b)   Crab              (c)   Leech                                      (d)   Tunicates Allometric growth is …

  Growth Meaning and definition of growth : Growth is an important properties of all living organisms. All organisms grow from a young stage to an adult stage. Growth is a permanent increase in dimensions of the body and its …

  Reproduction is the process of formation of new individuals from pre-existing ones. It is the means of multiplication and perpetuation of the species because the older individuals of each species undergo senescene and die. There are two basic types …

Pollen embryoids were discovered by (a)   Guha and Maheshwari      (b)   Steward and White (c)   Konar and Natraja              (d)   Nitsch and Skoog The embryo may arise either from egg or some other cell of gametophyte in (a)   Vegetative reproduction (b)   Recurrent …

Growth can be defined as a vital process which brings about irreversible permanent change in any plant or its part with respect to its size, form, weight and volume. Regions of growth : In unicellular plants there is overall growth …

  Reiter first used the term ecology in 1868. Ernst Haeckel (1886) first correctly defined ecology as “the science dealing with reciprocal relationship of organisms and the external world”. Prof. R.Misra is known as “Father of ecology in India”. Other …

  Ecological plants groups Water as an important ecological factor was first recognized by Warming. On the basis of water requirement plants are divided in to 3 major types : (1) Hydrophytes : They live in abundance of water. They …

  The word ecosystem was coined by A.G. Tansley in 1935. According to Odum an ecosystem is the basic fundamental unit of ecology which includes both the organisms and the non–living environment each influencing the properties of the other and …

Change in physical, chemical or biological characteristics of air, water and land that has the potentiality to harm human life, lives of other desirable species, industrial processes, living conditions, cultural assests and natural resources is called pollution. Pollutant : Pollutant …

  Anything which is useful to man or can be transformed into a useful product or can be used to produce a useful thing can be referred to as a resource. A natural resource is the resource obtained from nature. …

  Biome Definition : Each of the major terrestrial ecosystems or distinctive terrestrial areas with their group of climax plants and associated animals constitutes biomes. A biome is the largest terrestrial community. Rainfall, temperature range, nature of soil, barriers, latitude …

Biodiversity and Wild Life Conservation Endemic plants are those which are  [BHU 1978; CPMT 1999]              (a)   Cosmopolitan in distribution              (b)   Restricted to certain area              (c)   Found in arctic region              (d)   Gregarious in habit Earth Summit at …

The ‘‘environment as a self sustaining system’’ is mainly preserved by              (a)   Man                                         (b)   Animals              (c)   Trees                                      (d)   Wild life The worst dangerous threat to wild life is by [Pb. PMT 2000]              (a)   Habitat destruction            (b)   …