Sexual Reproduction in Flowering Plants — BIOLOGY STD 12 Science — Question

What is integrated organic farming?

Explain any two devices by which autogamy is prevented in flowering plants.

Why dogs and cats have oestrus cycle but human beings have menstrual cycle, though all are mammals?

pairs of contrasting characters of:

1. Position of flowers.
2. Colours of pod.
3. Shape of pod.
4. Colour of seed, that were selected in pea plant by Mendel.

Describe the structure of a seminiferous tubule

In the biosphere immense biological diversity exists at all levels of biological organisation. Explain any two levels of biodiversity.

Given below are the events in human reproduction. Write them in correct sequential order.
Insemination, gametogenesis, fertilisation, parturition, gestation, implantation.

Differentiate between:

1. Hypocotyl and coleoptile.
2. Protandry and protogyny.

In the following diagram the two DNA strands represented are ready for transcription.

1. Label the parts marked 1 to 4 and state their functions in transcription.
2. Which one of the two strands of DNA has nucleotide sequence similar to the mRNA that will be transcribed and why?

In peas, tallness is dominant over dwarfness, and red colour of flowers is dominant over the white colour. When a tall plant bearing red flowers was pollinated by a dwarf plant bearing white flowers, the different phenotypic groups were obtained in the progeny.
Tall, Red = 138
Tall, White = 132
Dwarf, Red = 136
Dwarf, White= 128
Mention the genotypes of the two parents and of the types of four off springs. in numbers mentioned against them.