Growth and development of organisms

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Reproduction Overview

All living organisms must reproduce to ensure their species does not become extinct.
There are two basic types: asexual reproduction (one parent, offspring identical) and sexual reproduction (two parents, offspring similar but not identical).
Asexual reproduction occurs in Archaea, Bacteria, Fungi, Protists, many plants/algae, and some animals (e.g., some insects, reptiles, sharks).
Sexual reproduction involves the fusion of male and female genetic information (DNA).
In angiosperms, flowers are the sexual organs, containing the structures needed for sexual reproduction.

Flower Structures

Flowers are typically set on a stalk called the peduncle.
The receptacle is the top part of the flower stalk, where the other flower parts attach.
Sepals are small, often green, leaf-like parts that protect the flower bud before it opens.
Petals are often brightly coloured to attract pollinators such as insects, birds, and bats; wind-pollinated flowers often have small or no petals because they do not need to attract animals.
Some flowers have both male and female parts; others have only male or only female parts, sometimes on separate plants.

Three flowers used to identify outer flower structures: a rose, water lilies, and petunias.

Male and Female Reproductive Structures

The stamen is the male part of the flower. It has two parts: the anther, which produces pollen containing the male sex cells, and the filament, a stalk that supports the anther.
The pistil (or carpel) is the female part of the flower, usually at its centre. It has three parts: the stigma, style, and ovary.
The stigma is the sticky tip that receives pollen during pollination.
The style is a long tube that connects the stigma to the ovary and supports the stigma in a good position to catch pollen.
The ovary is the enlarged base of the pistil. It contains ovules, and inside each ovule is an embryo sac where the seed will develop after fertilisation.

The female flower parts making up the pistil: stigma, style and ovary.

Pollination

Pollination is the transfer of pollen from the stamen to the stigma of a flower (same or different plant).
Pollination is essential for fertilisation and seed production; without it, no seeds or fruit form.
Pollination can occur via animals (pollinators like bees, birds, bats), wind, or water.
Animal-pollinated flowers often have bright petals, sweet scents, and nectar to attract pollinators; pollen is often sticky to cling to animals.
Wind-pollinated flowers are usually small, not colorful, produce large amounts of light, smooth pollen, and have feathery stigmas and hanging anthers to catch wind-borne pollen.
Water-pollinated plants release pollen that floats on water surface; stigmas are near the water surface.

Photos of grass, pampas grass, and maize flowers pollinated by wind.

Fertilisation in Plants

After pollination, a pollen tube grows from the pollen grain down the style to the ovule.
The pollen tube delivers male sex cells to the ovule; one fuses with the female sex cell in the embryo sac – this is fertilisation.
The fertilised egg develops into a seed; the other male cell fuses to form endosperm (starchy food for the germinating seed).
The ovary swells and becomes a fruit; ovules become seeds.
Fruits and seeds are adapted for dispersal to spread to new areas.

Diagram of a pollen tube growing from the stigma down the style to the ovules in the ovary.

Seed Dispersal

Seed dispersal spreads seeds away from the parent plant to reduce competition and colonise new areas.
Methods include: gravity (fruit falls and rolls), animals (eating fruit and excreting seeds, or seeds sticking to fur), explosive force (pods burst and shoot seeds), wind (light seeds with wings), and water (floating seeds).
Seeds have adaptations like tough outer coverings to survive animal digestion, hooks to cling to fur, or wings for wind dispersal.
Fruits attract animals to eat them, aiding in seed dispersal.

Dandelion, maple tree, and burdock seeds, each adapted for a different method of dispersal.

Adaptations for Reproduction

Plants attract pollinators and seed-dispersing animals with adaptations such as bright flowers, nectar, scents, and nutritious fruit; some plants also produce hard-shelled nuts that squirrels bury and sometimes forget, giving the seed a chance to grow.
Animals have courtship behaviours that help them attract a mate, such as a peacock raising its tail feathers, a blue-footed booby's dance, or the mating songs of whales and frogs.
Parental care increases the chances offspring survive: many birds and mammals build nests, feed their young, and protect them from predators.
Some parents use distraction behaviours to protect their young — a mother killdeer will feign a broken wing to lure a predator away from her nest, then fly off once the predator is far enough away.
Teaching young important skills also improves survival, such as meerkat parents teaching their pups how to safely eat scorpions.

A mother killdeer feigning a broken wing to lure a predator away from her nest.

Environmental and Genetic Factors in Growth

How an organism grows and develops depends on both genetic factors (the traits it inherits from its parents) and environmental factors (conditions such as light, water, temperature, and available nutrients).
A genetic factor is present regardless of surroundings — for example, some tree species can photosynthesise through their bark even in winter with no leaves, a trait every member of that species has.
Environmental factors can speed up or slow down growth without changing an organism's genes — for example, more available food or water generally allows faster growth, while crowding or a lack of resources can slow it.
Scientists can work out whether a difference in growth between two organisms is genetic or environmental by checking whether the individuals differ in their genes, their surroundings, or both.

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Câu hỏi luyện tập

Xem trước miễn phí — 8 trên 42 câu hỏi. Đăng ký để xem tất cả.

1.What is the term for the male reproductive part of a flower?
Easy
- AStamen
- BPistil
- COvary
- DSepal
2.What is the name of the structure that receives pollen during pollination?
Easy
- AStigma
- BStyle
- COvary
- DAnther
3.Sepals are often green and can photosynthesize.
Easy
True or false?
4.Which of the following is NOT a method of seed dispersal mentioned in the source?
Easy
- AGravity
- BExplosive force
- CPhotosynthesis
- DWind
5.Why do wind-pollinated flowers often have small or absent petals?
Easy
- ATo reduce water loss
- BBecause they do not need to attract animal pollinators
- CTo make them lighter for wind dispersal
- DTo prevent self-pollination
6.Which of the following are adaptations of wind-pollinated flowers? (Select all that apply)
Medium
- ALong filaments that hang down
- BFeathery stigmas
- CBrightly colored petals
- DSmooth, light pollen
- EProduction of nectar
7.A seed has a tough outer covering and spiky structures that stick to animal fur. How is this seed most likely dispersed?
Medium
- ABy wind
- BBy water
- CBy animals
- DBy explosive force
8.In sexual reproduction, offspring are identical to the parent.
Medium
True or false?

Thêm câu hỏi

9.Which of the following is an example of a courtship behavior?
Hard
- AA bee collecting nectar
- BA peacock raising its tail feathers
- CA bird building a nest
- DA seed sticking to fur
10.Match each flower structure to its primary function.
Medium
- Petal
- Stigma
- Ovary
- Anther
- Attract pollinators
- Receive pollen
- Produce ovules
- Produce pollen
11.A plant has flowers with large, white petals that open at night and produce a strong, sweet scent. Which pollinator is most likely responsible for pollinating this flower?
Medium
- ABees
- BMoths
- CBirds
- DWind
12.A farmer observes that his apple trees are producing fewer fruits. Which of the following factors could be responsible for the reduced fruit production? (Select all that apply)
Medium
- AA decline in the number of bees in the area
- BAn increase in the number of butterflies
- CHeavy use of pesticides that kill insects
- DPlanting wind-pollinated crops nearby
- ERemoving all flowering plants from the vicinity
13.In angiosperms, the ovary develops into the fruit after fertilisation.
Easy
True or false?
14.A farmer wants to increase the yield of a crop that is pollinated by insects. Which of the following actions would be most effective in increasing pollination?
Hard
- APlanting the crop in a field with high wind
- BProviding nesting sites for wild bees near the field
- CUsing pesticides to eliminate all insects
- DPlanting the crop in a greenhouse with no insects
15.Using the table above, on which day did the plant grow the most?
Medium
- ADay 3-4
- BDay 4-5
- CDay 5-6
- DDay 6-7
16.Which of the following are appropriate steps in a flower dissection to observe the ovules? (Select all that apply)
Medium
- ARemove the sepals and petals
- BCut the ovary in half with a knife
- CUse a dissecting needle to open the ovary
- DPlace the flower in a beaker of water
- ELabel the ovary and ovule on a diagram
17.Match each seed dispersal method to its adaptation.
Medium
- Animal dispersal
- Wind dispersal
- Explosive dispersal
- Tough outer covering or hooks
- Light seeds with wings
- Seed capsules that burst open
18.Arrange the steps of the pollen tube growth and fertilisation in angiosperms in the correct order.
Medium
- Pollen grain lands on the stigma
- Pollen tube grows down the style
- Pollen tube bursts into the ovule
- One male sex cell fertilises the female sex cell
- The fertilised egg develops into a seed
19.What is the independent variable in this investigation?
Medium
- AThe number of seeds
- BThe amount of light
- CThe number of days
- DThe temperature
20.If 8 seeds germinate in Tray A and 9 in Tray B, what conclusion can you draw?
Medium
- ALight is necessary for germination
- BLight is not necessary for germination
- CSeeds need light to grow
- DSeeds need darkness to germinate
21.A scientist observes that a species of flower has deep, tube-shaped corollas and produces nectar at the base. Which pollinator is most likely to pollinate this flower?
Hard
- AA bee with a short tongue
- BA butterfly with a long proboscis
- CA wind current
- DA beetle that crawls over the flower
22.A region's wild bee and butterfly populations collapsed over several years, and crop yields fell for three years in a row afterwards. Why would the loss of these pollinators lead to crop failures?
Medium
- ABecause crops could no longer photosynthesize
- BBecause crops could not be pollinated to produce seeds
- CBecause crops were infected with diseases
- DBecause crops were eaten by insects
23.Complete the sentence with the correct term.
Easy
The ____ is the top part of the flower stalk where the different flower parts attach.
24.What is the name of the process by which pollen is transferred from the stamen to the stigma?
Medium
25.How many male sex cells does each pollen grain contain in angiosperms?
Medium
26.What is the term for the starchy food stored in a seed that nourishes the germinating seedling?
Medium
27.The Sandbox tree can fling its seeds at speeds of up to 252 km/h. Convert this speed to m/s.
Medium
28.What is the term for the process when a seed starts to grow?
Easy
29.Complete the sentence about seed dispersal.
Easy
Seeds that are dispersed by ____ often have wings or are very light and small.
30.A researcher observes that a population of 1000 flowering plants produces 5000 seeds in one season. If each plant produces the same number of seeds, how many seeds does each plant produce?
Medium
31.Using the table above, what is the total growth of the plant from day 1 to day 14?
Medium
32.Complete the sentence about the function of the style.
Easy
The ____ supports the stigma and connects it to the ovary.
33.Explain how a mother killdeer protects her chicks from predators.
Hard
34.Explain how the structures of wind-pollinated flowers differ from those of animal-pollinated flowers, and why these differences are necessary.
Hard
35.Describe the trend in growth shown in the table above and suggest a reason for the pattern.
Hard
36.Explain the difference between pollination and fertilisation in plants.
Medium
37.How many male sex cells does each pollen grain contain in angiosperms?
Medium
- A3
- B2
- C4
- D1
38.The Sandbox tree can fling its seeds at speeds of up to 252 km/h. Convert this speed to m/s.
Medium
- A84 m/s
- B77 m/s
- C63 m/s
- D70 m/s
39.A researcher observes that a population of 1000 flowering plants produces 5000 seeds in one season. If each plant produces the same number of seeds, how many seeds does each plant produce?
Medium
- A6 seeds
- B5 seeds
- C7 seeds
- D4 seeds
40.What is the total growth of the plant from day 1 to day 14? (Day 1 height: 0 cm, Day 14 height: 12 cm)
Medium
- A12 cm
- B11 cm
- C13 cm
- D14 cm
41.The quaking aspen is a tree common in cool, moist parts of North America. Its bark is thin enough that sunlight can reach the cells underneath, so the tree can keep photosynthesising through the winter even after it has dropped its leaves. Quaking aspens grow faster than many other tree species and thrive in cool, moist, sunny conditions. Which statement provides evidence for how a genetic factor influences the growth of the quaking aspen?
Medium
- AThe quaking aspen can produce sugars needed for growth even in winter, when many other trees cannot.
- BLimited sunlight in winter causes the quaking aspen to produce less energy, slowing its growth.
- CThe trembling of its leaves in light breezes creates a cooler microclimate around the tree.
- DA lack of water during a drought would reduce how much a quaking aspen grows.
42.A student compares brook trout living in two ponds, Pond A and Pond B. The average size of the trout in Pond A is larger than in Pond B. The student lists factors that could explain the size difference: 1. Pond A has three times the surface area of Pond B. 2. There is more food available for trout in Pond A than in Pond B. 3. The trout in Pond A carry different genes than the trout in Pond B. 4. Pond A has a different predator species than Pond B. Which of these are environmental factors (rather than genetic factors)?
Medium
- Afactors 1 and 3 only
- Bfactors 2 and 4 only
- Cfactors 1, 2, and 3
- Dfactors 1, 2, and 4

Ghi chú ôn tập

## Growth and Development of Organisms ### Key Concepts - **Growth and development** are influenced by both **genetic factors** (DNA, genes) and **environmental factors** (light, temperature, nutrients). - **Animal behaviors** (e.g., pollination by bees) and **plant structures** (e.g., flowers, seeds) are crucial for successful reproduction. ### Developmental Processes 1. **Cell Differentiation**: Process where cells become specialized (e.g., nerve, muscle). Differentiated cells produce specific proteins (e.g., NeuroD for neurons, myogenin for muscle). Controlled by transcription factors and signaling pathways like Notch. 2. **Tissue Growth**: Increase in size via cell proliferation, cell size changes, or extracellular material deposition. Includes allometry (differential growth of parts). 3. **Morphogenesis**: Formation of three-dimensional shape. In animals, involves cell sheet movements; in plants, achieved by differential growth (cells are immotile). 4. **Regional Specification**: Creation of spatial patterns in cell sheets via cytoplasmic determinants and inductive signals. Early stages produce committed cell populations expressing specific transcription factors. ### Regeneration - Ability to regrow missing parts. Common in plants and some animals (e.g., Hydra, planarians). In amphibians, each cell type regenerates itself except connective tissues. - Debate: Is regeneration a primitive or adaptive trait? ### Key Terms - **Transcription factors**: Proteins that bind to DNA to activate or repress gene expression. - **Stem cells**: Undifferentiated cells that can differentiate into various cell types. - **Notch signaling**: Pathway involved in lateral inhibition during cell differentiation. ### Examples - **Pollination**: Bees transfer pollen, enabling fertilization. - **Seed dispersal**: Wind, animals, or water spread seeds to new locations.

Cell differentiation: The process by which cells become specialized into distinct functional types (e.g., nerve, muscle) through the activation of specific genes and production of characteristic proteins.
Morphogenesis: The development of the three-dimensional shape of an organism, involving coordinated cell movements (animals) or differential growth (plants).
Regional specification: The processes that create spatial patterns in a group of initially similar cells, often involving cytoplasmic determinants and inductive signals, leading to committed cell populations.
Regeneration: The ability of an organism to regrow a missing body part, such as a limb or tail.
Transcription factor: A protein that binds to specific DNA sequences to control the rate of transcription of genetic information, thereby regulating gene expression.
Stem cell: An undifferentiated cell capable of dividing and giving rise to multiple specialized cell types.
Notch signaling pathway: A cell signaling system that mediates lateral inhibition, controlling the formation of different cell types from a common progenitor.

Thẻ ghi nhớ

What are the two main factors that influence the growth of organisms?

Environmental factors and genetic factors.

Give an example of an animal behavior that contributes to successful reproduction.

Pollination by bees or other animals.

What plant structures are involved in seed dispersal?

Fruits, wings, or hairs that help seeds travel by wind, water, or animals.

What is developmental biology?

The scientific study of processes by which animals and plants grow and develop.

Name four phenomena studied in developmental biology.

Regeneration, asexual reproduction, metamorphosis, and growth/differentiation of stem cells.

What are the three main processes in animal embryonic development?

Tissue patterning (regional specification and cell differentiation), tissue growth, and tissue morphogenesis.

What is regional specification?

The creation of spatial patterns in a sheet of similar cells, often involving cytoplasmic determinants and inductive signals.

What is cell differentiation?

The formation of functional cell types like nerve, muscle, or liver cells, characterized by production of specific proteins.

What is morphogenesis?

The formation of three-dimensional shape through orchestrated movements of cell sheets and individual cells.

How does tissue growth occur?

Mainly through cell proliferation, but also via changes in cell size or deposition of extracellular materials.

How does plant development differ from animal development regarding cell movement?

Plant cells are mostly immotile, so morphogenesis is achieved by differential growth, not cell movements.

What is generative biology?

The generative science exploring dynamics guiding development and evolution of biological morphological form.

What is a key transcription factor for neuronal differentiation?

NeuroD.

What is a key transcription factor for muscle differentiation?

Myogenin.

What is a key transcription factor for hepatocyte (liver cell) differentiation?

HNF4.

What is lateral inhibition in cell differentiation?

A process based on Notch signaling that controls formation of different cell types from a single progenitor or stem cell.

What is regeneration?

The ability to regrow a missing part, common in plants and some animals like hydra and planarians.

Which two organisms can regenerate whole bodies?

Hydra and planarian worms.

What are stem cells?

Cells that can continuously divide and differentiate into various cell types; some are pluripotent.

What is the difference between 'pristine' and 'adaptive' views of regeneration?

Pristine view: regeneration is a general property that could be enhanced in humans. Adaptive view: each instance evolved by natural selection for specific species.

What are the three germ layers formed during morphogenesis?

Ectoderm, mesoderm, and endoderm.

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