Chapter 2 - Digital Commons @ Michigan Tech
... Figure 21. Polytrichum piliferum in a dry state. Water is slow to penetrate these leaves with a thin waxy coating. Photo by Janice Glime. ...
... Figure 21. Polytrichum piliferum in a dry state. Water is slow to penetrate these leaves with a thin waxy coating. Photo by Janice Glime. ...
Evolutionary mysteries in meiosis.
... their subsequent radiation over one billion years ago [3–5]. Extant eukaryotes share a set ...
... their subsequent radiation over one billion years ago [3–5]. Extant eukaryotes share a set ...
Evolutionary mysteries in meiosis.
... proto-meiosis–endoreplication cycle evolved to switch between ploidy levels [5]. The resulting life cycle may have resembled modern ‘parasexual’ fungi in which diploid cells lose chromosomes in subsequent mitotic divisions, leading to haploidy via aneuploid intermediates [15]. Many other modern euka ...
... proto-meiosis–endoreplication cycle evolved to switch between ploidy levels [5]. The resulting life cycle may have resembled modern ‘parasexual’ fungi in which diploid cells lose chromosomes in subsequent mitotic divisions, leading to haploidy via aneuploid intermediates [15]. Many other modern euka ...
dr. arvind`s biology classes
... b) It is identical to normal mitosis c) It starts when the egg reaches uterus d) It starts while the egg is in Fallopian tube Ans. (d) ...
... b) It is identical to normal mitosis c) It starts when the egg reaches uterus d) It starts while the egg is in Fallopian tube Ans. (d) ...
Pollen and seed desiccation tolerance in relation
... dryness. Mechanisms to survive and remain in a vigorous condition when water is lacking became important as life moved onto the land (Footitt and Cohn, 2001) and were indispensable for the evolution of land plants (Hoekstra, 2002). From an evolutionary point of view, it is very difficult to say whet ...
... dryness. Mechanisms to survive and remain in a vigorous condition when water is lacking became important as life moved onto the land (Footitt and Cohn, 2001) and were indispensable for the evolution of land plants (Hoekstra, 2002). From an evolutionary point of view, it is very difficult to say whet ...
Navodaya Vidyalaya Samiti – Bhopal Region.
... *Spermatogenesis- The process of sperm formation takes place in seminiferous tubules of testis which is lined by germinal epithelial consisting immature male germ cells spermatogonia. Spermatogonia (2n) undergoes mitosis & increase in number.Some spermatogonia,called as primary spermatocyte undergoe ...
... *Spermatogenesis- The process of sperm formation takes place in seminiferous tubules of testis which is lined by germinal epithelial consisting immature male germ cells spermatogonia. Spermatogonia (2n) undergoes mitosis & increase in number.Some spermatogonia,called as primary spermatocyte undergoe ...
Gibberellin induces diploid pollen formation by
... for the growth and maturation of the developing microspores. Moreover, GA is also known to operate as a stress signaling molecule upon exposure to abiotic stresses (cold, salt and osmotic stresses) either triggered by alterations in GA biosynthesis or its downstream signaling pathway. For example, c ...
... for the growth and maturation of the developing microspores. Moreover, GA is also known to operate as a stress signaling molecule upon exposure to abiotic stresses (cold, salt and osmotic stresses) either triggered by alterations in GA biosynthesis or its downstream signaling pathway. For example, c ...
And Hast Thou Slain the Jabberwock? Response to Wallen
... adaptation–it must have a genetic basis, influence reproductive success, and so on–“are, in fact, requirements to show that natural selection is currently operating on a character, not to show that selection has shaped the character over the evolutionary history of the species” (Puts, 2006, p. 104). ...
... adaptation–it must have a genetic basis, influence reproductive success, and so on–“are, in fact, requirements to show that natural selection is currently operating on a character, not to show that selection has shaped the character over the evolutionary history of the species” (Puts, 2006, p. 104). ...
ANTIFERTILITY POTENTIAL OF SOME MEDICINAL PLANTS IN MALES: AN OVERVIEW
... actively pursue research towards new contraceptive approaches4. Current methods of contraception result in an unacceptable rate of unintended pregnancies and many side effects also5,6. A large number of chemical agents have been known but all tend to lead to total spermatogenic arrest and, ultimatel ...
... actively pursue research towards new contraceptive approaches4. Current methods of contraception result in an unacceptable rate of unintended pregnancies and many side effects also5,6. A large number of chemical agents have been known but all tend to lead to total spermatogenic arrest and, ultimatel ...
Polyandry as a mediator of sexual selection before and after mating
... Figure 1. Operational sex ratio (OSR) is a central concept for understanding variation in mating competition and sexual selection within and between species. OSR is the ratio (m : f ) or proportion (m/m þ f ) of males and females that are ready to mate in a population at any one time [4,9]. In many ...
... Figure 1. Operational sex ratio (OSR) is a central concept for understanding variation in mating competition and sexual selection within and between species. OSR is the ratio (m : f ) or proportion (m/m þ f ) of males and females that are ready to mate in a population at any one time [4,9]. In many ...
Journal of Molluscan Studies
... are present, they vary in number and length, as well as in presence of additional perpendicular blades, enlarging the surface area and possibly the amount of mucus that can be transferred. In general, families other than the Helicidae typically carry simpler darts with a smooth surface. In addition, ...
... are present, they vary in number and length, as well as in presence of additional perpendicular blades, enlarging the surface area and possibly the amount of mucus that can be transferred. In general, families other than the Helicidae typically carry simpler darts with a smooth surface. In addition, ...
Cytoplasmic Ca changes dynamically during the
... growth, but they fail to rupture and release the sperm cells (Schiøtt et al., 2004). This finding suggests the involvement of Ca2+ signaling in sperm discharge. The relationship between [Ca2+] and pollen tube growth has previously been examined in vitro, where pollen tubes germinate and grow in cult ...
... growth, but they fail to rupture and release the sperm cells (Schiøtt et al., 2004). This finding suggests the involvement of Ca2+ signaling in sperm discharge. The relationship between [Ca2+] and pollen tube growth has previously been examined in vitro, where pollen tubes germinate and grow in cult ...
Remember – The Caya® diaphragm does not protect against STIs
... accepts no responsibility for difficulties that may arise as a result of an individual acting on the advice and recommendations it contains. ...
... accepts no responsibility for difficulties that may arise as a result of an individual acting on the advice and recommendations it contains. ...
Gamete competition, gamete limitation
... a whole suite of secondary sexual traits exists, but the fundamental definition is rooted in this difference in gametes, and the question of the origin of the two sexes is then equal to the question of why do gametes come in two different sizes. This gamete size dimorphism is called anisogamy, and i ...
... a whole suite of secondary sexual traits exists, but the fundamental definition is rooted in this difference in gametes, and the question of the origin of the two sexes is then equal to the question of why do gametes come in two different sizes. This gamete size dimorphism is called anisogamy, and i ...
Developmental Evolution of the Sexual Process in
... Recent investigations of ancient angiosperm lineages are yielding data critical to a fundamental reassessment of the origin and early evolution of flowering plants. To ‘‘reconstruct’’ the reproductive features of the earliest flowering plants, biological characters must be examined in an appropriate ...
... Recent investigations of ancient angiosperm lineages are yielding data critical to a fundamental reassessment of the origin and early evolution of flowering plants. To ‘‘reconstruct’’ the reproductive features of the earliest flowering plants, biological characters must be examined in an appropriate ...
197 THE ROLE OF Ca2+ IN SIGNAL TRANSDUCTION FOLLOWING
... 1990) is present, but information is lacking concerning its distribution. The electrical properties of the Fucus serratus egg show similarities with those of several animal eggs. The Fucus serratus egg plasma membrane contains voltage-gated channels and can elicit action-potential-like voltage respo ...
... 1990) is present, but information is lacking concerning its distribution. The electrical properties of the Fucus serratus egg show similarities with those of several animal eggs. The Fucus serratus egg plasma membrane contains voltage-gated channels and can elicit action-potential-like voltage respo ...
zygote special wall
... time as a possible anomaly of the pollen-tube tip within the embryo sac, or a callose deposit within the ovum stimulated by incompatible pollen tube/embryo sac interaction. Subsequent work with a greater range of compatibly pollinated materials has shown this phenomenon to be characteristic of norma ...
... time as a possible anomaly of the pollen-tube tip within the embryo sac, or a callose deposit within the ovum stimulated by incompatible pollen tube/embryo sac interaction. Subsequent work with a greater range of compatibly pollinated materials has shown this phenomenon to be characteristic of norma ...
Male birch catkin bugs vary copula duration to invest more in
... male and female mating partner, and the sexes may frequently disagree over the optimal outcome. Here we report the results of experiments designed to establish which sex controls copula duration in the birch catkin bug, Kleidocerys resedae, and to test for strategic investment by the controlling sex ...
... male and female mating partner, and the sexes may frequently disagree over the optimal outcome. Here we report the results of experiments designed to establish which sex controls copula duration in the birch catkin bug, Kleidocerys resedae, and to test for strategic investment by the controlling sex ...
Evolution of egg dummies in Tanganyikan cichlid fishes: the roles of
... the stage for intense sexual selection in mouthbrooding species (Oppenheimer, 1970). To exert mate choice, females can use indicators of mate quality such as morphology, behaviour or territory size prior to mating (Andersson, 1994) or post-mating through cryptic female choice (Eberhard, 1996). Durin ...
... the stage for intense sexual selection in mouthbrooding species (Oppenheimer, 1970). To exert mate choice, females can use indicators of mate quality such as morphology, behaviour or territory size prior to mating (Andersson, 1994) or post-mating through cryptic female choice (Eberhard, 1996). Durin ...
edulabz - Testlabz.com
... Ans. 1. bisexual 2. unisexual 3. pollination 4. fertilization 5. seed. V. Which of the following statements are true (T) and which ones are false (F)? Mark T or F: 1. Asexual reproduction is more common than the sexual reproduction. 2. Producing life is called respiration. 3. Dogs and cats reproduce ...
... Ans. 1. bisexual 2. unisexual 3. pollination 4. fertilization 5. seed. V. Which of the following statements are true (T) and which ones are false (F)? Mark T or F: 1. Asexual reproduction is more common than the sexual reproduction. 2. Producing life is called respiration. 3. Dogs and cats reproduce ...
video slide - Summit Public Schools
... secondary compounds evolved in many plant species • Symbiotic associations between fungi and the first land plants may have helped plants without true roots to obtain nutrients ...
... secondary compounds evolved in many plant species • Symbiotic associations between fungi and the first land plants may have helped plants without true roots to obtain nutrients ...
Chapter 29 - Cloudfront.net
... secondary compounds evolved in many plant species • Symbiotic associations between fungi and the first land plants may have helped plants without true roots to obtain nutrients ...
... secondary compounds evolved in many plant species • Symbiotic associations between fungi and the first land plants may have helped plants without true roots to obtain nutrients ...
Life history evolution in a bivoltine butterfly
... during the favourable time of year and diapause during unfavourable periods. As a consequence of this the production of more than one generation per year involves a choice between alternative developmental pathways, direct development or diapause. If a genotype produces individuals who are able to c ...
... during the favourable time of year and diapause during unfavourable periods. As a consequence of this the production of more than one generation per year involves a choice between alternative developmental pathways, direct development or diapause. If a genotype produces individuals who are able to c ...
Sex roles and sexual selection
... found in his studies of Drosophila melanogaster that multiple copulations led to a greater increase in the number of offspring produced in males than in females. Hence, he concluded that there is a greater advantage for males in copulating with several partners than there is for females, leading to ...
... found in his studies of Drosophila melanogaster that multiple copulations led to a greater increase in the number of offspring produced in males than in females. Hence, he concluded that there is a greater advantage for males in copulating with several partners than there is for females, leading to ...
Fertilisation
Fertilisation (also known as conception, fecundation and syngamy) is the fusion of gametes to initiate the development of a new individual organism. In animals, the process involves the fusion of an ovum with a sperm, which first creates a zygote and then leads to the development of an embryo. Depending on the animal species, the process can occur within the body of the female in internal fertilisation, or outside (external fertilisation). The cycle of fertilisation and development of new individuals is called sexual reproduction.