Ch 1. Reproduction in Organisms Flashcards
Define reproduction
The biological process in which an organism gives rise to offspring similar to itself.
What is the significance of reproduction?
It is responsible for the continuation of life
What is a life span?
The period from birth to the natural death of organisms
What is asexual reproduction?
When an offspring is produced by a single parent without the formation and fusion of gametes.
What is sexual reproduction?
When two parents (opposite sex) participate in the reproductive process involving the fusion of male and female gametes..
Offsprings produced from asexual reproduction are clones.
Why?
Offsprings produced from asexual reproduction are produced from a single parent and are genetically and morphologically identical to the parent.
Name two organisms in which cell division itself is a mode or reproduction.
- protists
- monerans
The parent cell divides into two giving rise to a new individual
Name an organism that undergoes asexual reproduction by means of
- conidia
- budding
- zoospores
- gemmules
- Conidia of Penicillium
- Budding in Hydra
- Zoospores of Chlamydomonas
- Gemmules in sponges
Which organism undergoes asexual reproduction by means of encystations and sporulation.
Amoeba
What is encystation?
When an Amoeba withdraws its pseudopodia and secretes a three layered hard covering or cyst around itself, due to unfavorable conditions
What is a gemmule?
Internal buds, composed of a cluster of cells, capable of giving rise to new individuals are called gemmules.
E.g., Fresh water sponges produce gemmules under unfavourable conditions.
What are vegetative propagules?
Give two examples.
Structures or units of vegetative propagation in plants that are capable of giving rise to new offspring
Ex: Runner rhizome, sucker, tuber, offset, bulb, etc.
Name the vegetative propagules in potato, ginger, water hyacinth, Agave, onion and Bryophyllum
Potato – eyes
Ginger – rhizome
water hyacinth – offset
Agave – bulbil
Onion – bulb
Bryophyllum – leaf buds
What is the juvenile phase of life span?
The period of growth of an organism from its birth to reproductive maturity
What is reproductive phase oflife span?
The duration in life during which an organism produces gametes and further progeny.
What is senescent phase of life span?
The post reproductive phase when ageing followed by death
Mention the scientific name of a plant which produces flowers once in twelve years?
Strobilanthus kunthiana (neelakuranji) found in the hilly areas of Kerala, Karnataka and Tamil Nadu.
Name the reproductive cycle that occurs in females which are seasonal
Oestrus cycle
What are seasonal breeders?
Animal species that mate and produce offspring only during certain times of the year
Ex: Lizards, frogs, rats, dogs, horses, sheep, goats, deer, etc.
What are continuous or non-seasonal breeders?
Animals that are reproductively active throughout the reproductive phase and can mate and produce offspring at any time of the year
E.g., poultry, cows, rabbits, monkeys, apes and human beings.
The process of formation of the male and female gametes in the primary sex organs is called __________________
Gametogenesis
Gametes that are similar in appearance and cannot be morphologically distinguished into male and female gametes are called __________________ or _____________
Ex: Cladophora (alga)
homogametes or isogametes
Gametes which are dissimilar in appearance and can be morphologically distinguished into male and female gametes are called ____________
Ex: Homo sapiens (humans)
heterogametes
What are monoecious plants and dioecious plants?
monoecious plants.
Plants in which both male and female flowers are borne on the same individual (E.g., Corn (maize). )
dioecious plants.
Plants in which the male and female flowers are borne on the different individuals (E.g., Papaya)
True or False:
Cucurbita is called dioecious plant
False:
Cucurbita is called monoecious plant
True or False:
Papaya plant is dioecious plant.
True: Papaya plant is dioecious plant.
Mention two examples of monoecious plants.
- Cucurbits
- Coconuts
- Chara
- Hibiscus
What is a staminate flower? Give one example.
A unisexual flower producing only stamens and no pistils
Ex: Cucumber
A unisexual flower producing only pistils and no stamens is called __________________
Ex: Corn
pistillate
What are hermaphrodites? Give example.
The animals species (bisexual) that possess both male and female reproductive organs in the same individual. E.g. Earthworm, Leech.
What are prefertilization events?
Prefertilization events are the events that precede the fusion of gametes. They are:
- Gametogenesis – formation of male and female gametes and
- Gamete transfer – bringing the male and female gametes together.
Specialized diploid cells present in the primary sex organs of sexually reproducing organisms, which undergo meiosis to produce haploid gametes are called _________
meiocytes
Number of male gametes are much higher to that of female gametes in organisms. Why?
During the movement of the male gametes towards the female gamete for fertilization, a large number of them are destroyed or lose their viability.
To compensate for this loss, the number of male gametes produced is much higher than that of female gametes.
Define fertilization or syngamy
Fertilization or syngamy refers to the fusion of male and female gametes resulting in the formation of a diploid zygote
What is parthenogenesis?
a form of asexual reproduction in which a female gamete develops into a new individual without fertilization.
Examples: honey bees, ants, birds.
External fertilization is disadvantageous compared to internal fertilization.
Why?
In external fertilization, formation and development of the zygote takes place outside the body of the female and hence the offspring are extremely vulnerable to predators in the environment.
the process of development of embryo from the zygote by cell division (mitosis) and cell differentiation is called ______________
Embryogenesis
What are oviparous animals? Give one example.
Oviparous animals are those that lay eggs and development of the zygote takes place outside the body of the female parent.
E.g., reptiles and birds.
What are viviparous animals? Give examples.
Viviparous animals are those in which the zygote develops inside the body of the female parent so that it directly gives birth to young ones.
Ex: Mammals
Which part of the flower develops into fruit?
Ovary
What is Pericarp?
the protective tissue which is formed from the wall of the ripened ovary surrounding the seed of a fruit.
Mention important differences between asexual reproduction and sexual reproduction.
Asexual Reproduction
- Only one individual participates in the reproductive process.
- It does not involve fusion of gametes.
Sexual Reproduction
- Two individuals of opposite sex participate in the reproductive process.
- It involves fusion of male and female gametes.
What are vegetative propagules?
Give two examples.
Vegetative propagules are negetative units of plants, capable of giving rise to new offsprings.
- runne
- rhizome
- sucker
- tubes
Write differences between menstrual and oestrous cycle.
Oestrus cycle
- It occurs in non-primates (cows, dogs, etc)
- Ovulation, copulation and production of offspring occurs only during the heat period.
- The endometrium shed is absorbed by the walls of the uterus.
Menstrual cycle
- It occurs in primates (Humans, apes, etc)
- Ovulation, copulation and offspring production can occur any time during the reproductive phase.
- The endometrium shed is expelled from the uterus along with blood.
List important differences between seasonal breeders and continuous breeders.
Seasonal Breeders
- These are the organisms which mate or breed during certain seasons of the year. E.g., Lizards, frogs, rats, dogs, horses, sheep, goats, deer, etc.
- The females have one or more oestrus cycles during the mating period.
- Both females and males are sexually active due to physiological changes only during the heat period and inactive at other times.
Continuous Breeders
- These are the organisms which mate or breed throughout the year irrespective of the season. E.g., poultry, cows, rabbits, monkeys, apes and human beings.
- The females have menstrual cycles throughout the reproductive phase.
- The females are sexually more receptive during ovulation while males do not undergo physiological changes and so remain active always.
Distinguish between homogametes and heterogametes.
Homogametes
- The male and female gametes are similar in appearance.
- They are produced by some algae and fungi.
- The common examples are Rhizopus and Ulothrix.
Heterogametes
- The male and female gametes are morphologically dissimilar.
- They are produced by the sexually developed organisms.
- The common examples are gymnosperms and angiosperms.
List differences between external and internal fertilization.
External Fertilization
- Fertilization takes place outside the body of the organism. Examples: Fish, Amphibians, and most of the Algae, etc.
- The developing zygote is exposed to predators and adverse environmental conditions.
- Survival chances of offspring is very low, hence millions of eggs are produced.
Internal Fertilization
- Fertilization takes place inside the body of the female parent. Examples: Reptiles, Birds, Mammals, Bryophytes, Pteridophytes, Angiosperms and Gymnosperms.
- The developing zygote is protected from predators and adverse environmental conditions.
- Survival chances of offspring is very high, hence only one or few eggs are produced.
List important differences between viviparous and oviparous modes of development.
Viviparous
- Animals gives birth to young ones
- Zygote does not develop within a calcareous shell.
- The development of zygote takes place inside the female body.
- Females deliver young ones and the chance of survival are more.
Oviparous
- Animals lays eggs.
- Zygote develops within a calcareous shell.
- The development of zygote takes place outside the female body.
- Females lay eggs m the safe place m the environment. But chance of survival are less.
